Steroids and “the Pill”: early steroid research at Searle Frank B. Colton G. D. Searle & Co., Chicago, Illinois, USA
The announcement from the Mayo Clinic in 1949 of the dramatic effectiveness of cortisone in the treatment of rheumatoid arthritis stimulated tremendous interest in steroid chemistry, endocrinology, and related areas of medicine. Shortly thereafter, G. D. Searle & Co. initiated a major effort in steroid research, the objective of which was to discover better steroid drugs than those available at that time or steroids that could be used for conditions for which no compounds were previously available. This effort was remarkably successful and resulted in the introduction of several important pioneering drugs. These included norethandrolone, marketed in 1956 as Nilevar, the$rst anabolic agent with a favorable separation between protein building and virilization, and spironolactone, introduced in 19.59 as Aldactone, the$rst steroid antialdosterone antihypertensive agent. Of special importance was the research that culminated in the discovery ofEnovid. This substance, a combination oftheprogestin norethynodrel and the estrogen mestranol was jirst approved in 1957 for the treatment of a variety of disorders associated with the menstrual cycle. The era of oral contraception began in May 1960, when Enovid was approved by the Food and Drug Administration for ovulation inhibition, and was immediately thereafter introduced for such use. (Steroids 57624-630, 1992)
Keywords:
steroids; Searle; Enovid; progesterone;
ovulation inhibition; birth control pill; oral contraceptive
Introduction I would like to describe the early steroid research at G. D. Searle & Co., with emphasis on the research that led to the discovery and development of the first oral contraceptive, Enovid, a substance that became popularly known as “the Pill.” The announcement from the Mayo Clinic in 1949 by Drs. Edward C. Kendall, Philip Hench and their associates’s2 of cortisone’s dramatic effectiveness in the treatment of rheumatoid arthritis touched off one of the greatest bursts of excitement in the entire history of drug therapy. Cortisone was acclaimed as one of the most significant discoveries of the generation. This discovery resulted in the 1950 award of the Nobel Prize in Physiology and Medicine to Drs. Kendall and Hench from the Mayo Clinic and to Dr. Tadeus Reichstein from Switzerland. I completed the requirements for the Ph.D. degree in organic chemistry from the University of Chicago in 1949, at the time when these dramatic results with cortisone were beginning to come out from the Mayo Clinic, and was extremely fortunate to have been invited by Kendall to join his group at the Mayo Clinic Address reprint requests Evanston, IL 60203.
624
Steroids,
to Dr. Frank B. Colton,
1992, vol. 57, December
39dl Lyons,
during this exciting period of steroid research. For a new Ph.D., the privilege to work at the Mayo Clinic at such an opportune time, on such an important problem, and with a scientist such as Kendall was indeed a dream come true. My assigned task was to develop an alternate and hopefully superior method to those available at that time for the introduction of the 17-hydroxyl group in the partial synthesis of cortisone. We were indeed fortunate to have succeeded in this objective.3-5 Understandably, the discovery of the exciting potential of cortisone stimulated tremendous interest in steroid chemistry, endocrinology, and related areas of medicine, and practically every leading pharmaceutical company and many research and medical centers throughout the world began active programs in these areas. G. D. Searle & Co., a small ethical pharmaceutical house located in Skokie, a suburb of Chicago, Illinois, also decided to get involved in steroid research. The total annual sales of Searle at that time were about $20,000,000. Although the company had a limited product line, most of its products were highly innovative and were developed as a result of its own research. One such innovative drug was Dramamine. This substance, the first antimotion sickness pill, was introduced in 1949 and still retains the dominant position in this field.
0 1992 Butterworth-Heinemann
Research at Searle on “The Pill”: Colton
Dr. Albert L, Raymond, the Vice-President of Research and Development at Searle, was convinced that steroids represented a promising growth area with great potential in medicine and he initiated steps to get the company involved in steroid research on a significant scale. In 1951 he hired Dr. Byron Riegel, a professor of chemistry from Northwestern University with research experience in steroids, to become Director of Chemical Research and Development. He also hired other senior scientists, both chemists and biologists, with experience in steroids. I was fortunate to have been invited to join this group of excellent scientists in 1951. Earlier, Raymond also succeeded in attracting as a consultant Dr. Gregory Pincus, the well known reproductive physiologist who was Director of the Worcester Foundation for Experimental Biology and Medicine. The overall objective of our steroid program was to discover, develop, and introduce into clinical use better steroid drugs than those available at the time and/or steroids that would be useful in conditions for which no compounds were previously available.6 Our pioneering steroid effort was, indeed, remarkably successful in its primary objective, and several important breakthrough drugs were developed and marketed. These included Nilevar, introduced in 1956, the first anabolic agent that had a favorable separation between its protein building and virilizing properties, and Aldactone, introduced in 1959, the first steroid antialdosterone antihypertensive agent. Of special importance, however, was the research which culminated in the introduction of Enovid, the first oral contraceptive _ It is now 40 years since norethynodrel, the progestin component of Enovid, was first synthesized. The preparation of norethynodrel and various related compounds was part of a planned program undertaken in the hope of developing an orally effective compound that would have progestational activity, inhibit ovulation, and would produce a reversible antife~ility effect in experimental animals. It was also our objective that such a compound should not have androgenic activity or other undesirable endocrine effects and no untoward toxicity in animal studies. It had been known since the beginning of this century that, in animal studies, extracts of the corpus luteum were capable of inhibiting ovulation. Shortly after pure progesterone (1)became available, Makepeace and his associates from the University of Pennsylvania showed that this substance, by injection, inhibits ovulation in the rabbit. In addition to ovulation inhibition, progesterone also has other impo~ant physiologic~ properties. For example, progesterone is necessary during pregnancy to prevent the spontaneous abortion of the implanted fertilized ovum. It is because of this property that progesterone has been referred to as the pregnancy hormone. Paradoxically, then, progesterone, at least in theory, can be used for both contraceptive and proceptive purposes. Despite the key role of endogenous progesterone in fertility control, the use of this natural hormone to
enhance fertility or for contraceptive purposes was not considered practical. For example, progesterone has very low activity when taken orally and, when given intramuscularly, it often causes a severe reaction at the site of injection. In an attempt to obtain molecules with greater effectiveness, numerous structural modifications of the progesterone molecule were prepared by early researchers and were investigated for progesteronelike activity. Unfortunately, most of these modifications resulted in either complete loss or marked diminution of biological activity.’ In view of the very high degree of structural specificity required for physiological activity, as shown by the lack of activity of so many closely related derivatives of progesterone, it was therefore completely unexpected that 17-ethynyltestosterone (2), a substance structurally different from progesterone but that instead resembles the male hormone testosterone (3), possessed progestational activity on oral administ~tion. Although the oral potency of this material was low, and the compound, as expected, had appreciable androgenic activity, this compound did possess considerably higher oral progestational activity than natural progesterone and was marketed in Europe in 1941 as ethisterone, a progestational agent for the treatment of certain female disorders. This compound was prepared in 1937 by Inhoffen and associates8t9 The finding of appreciable oral progestational activity for ethisterone was an important observation, which guided subsequent work in the 1Pnor steroid area.
I
2
3
In 1944 Professor Maximili~ Ehrenstein from the University of Pennsylvania succeeded in the conversion of the cardiac aglycone, strophanthidin (4), in a 0.07% yield into a resin that he believed to be 19norprogestone (5).” Ehrenstein’s compound appeared impure and its structure was uncertain. Nevertheless, this compound was at least as potent a progestational agent in the rabbit, by injection, as natural progesterone. This finding of such high progestational activity of Ehrenstein’s compound was of special significance, because it was known that relatively minor structural changes in the progesterone molecule were often accompanied by marked reduction or complete elimination of biological activity. Such high activity of a 19-nor steroid was an important structural clue in the discovery of oral contraceptives.
Steroids, 1992, vol. 57, December
625
Papers
In 1949 Birch and Mukherji” from England described a method for the conversion of estradiol into a 1,4-dihydro steroid. Shortly thereafter, Birch” described the transformation of this 1,4-dihydro derivative into 19-nortestosterone (6). Birch also indicated that his objective was to prepare additional 19-nor steroids from estrone to ascertain whether the expenditure of effort necessary for the complete synthesis of such 19-nor analogues was justified. In 1951, Birch and his student, Herschel Smith,13 stated that 19-nortestosterone possessed appreciable androgenic activity. This activity was reported elsewhere to be considerably less than testosterone. “1’5 on
LP n
0
Shortly after the publications by Birch, Professor Alfred Wilds and his student, Norman Nelson from the University of Wisconsin, improved on the Birch method of reduction.15 Wilds informed Jack Ralls, one of his former students who joined our steroid group, about his improved Birch procedure before publication. We and, I understand, the Syntex researchers used the Wilds-Nelson modification of the Birch reduction in the early studies with 19-nor steroids. To recapitulate, the observation of the unexpected oral progestational activity of 17-ethynyltestosterone and the high parenteral progestational activity of Ehrenstein’s “19-not-progesterone” suggested to us at Searle and, independently, to the Syntex investigators that the combination of these structural clues might afford a clinically useful new class of compounds. Furthermore, the synthetic advances of Birch and of Wilds and Nelson afforded the means for the preparation of such molecules.
Norethynodrel, Enovid, Norethandrolone, 19-norhydrocortisone One of the early objectives of our steroid research was to study the effects of various structural parameters on the biological properties of steroid hormones in the hope of improving the therapeutic effectiveness of these substances.6 The 19-nor steroids appeared to offer promise as potentially useful therapeutic agents and we decided to prepare several key compounds in this area. We were not interested in potency alone but hoped that certain of these compounds would have a better profile of biological activity than the natural compounds. We were aware of the interest in 19-nor steroids by other laboratories, but we nevertheless decided to enter this competitive area because we were confident we could make a significant contribution. Improvement on the biological profile of cortisone or hydrocortisone was one of our objectives in the antiinflammatory area. We believed that the 19-nor an626
Steroids,
1992, vol. 57, December
alog of hydrocortisone (7) was a promising candidate in this regard, and we devised a synthesis that we believed was unique and that incorporated both chemical and biochemical methodology. Furthermore, our synthetic approach for 1Pnorhydrocortisone was such that it could readily be adapted for the preparation of other potentially valuable 19-nor steroids in the progestational, estrogenic, anabolic, and antihypertensive categories. These areas were of considerable interest to us and were on a comparable priority with our interest in the antiinflammatory area. We developed in-house testing capability for the biological evaluation of such compounds. In addition we submitted selected compounds to Pincus and Chang of the Worcester Foundation for Experimental Biology and Medicine for screening for ovulation inhibition in the rabbit.
The 3-methyl ether of estradiol (8) was reduced by the Wilds-Nelson modification of the Birch reduction” to the dihydro enol ether (9).
a
9
10
Careful Oppenauer oxidation of this sensitive enol etheri afforded a good yield of the 3-methyl ether of 1,4_dihydroestrone (10). This compound was a key intermediate for the synthesis of many of our Asoo) and 19-nor-A4 steroids. The 17-ethynyl group was introduced by reacting the 17-keto derivative with acetylene under basic conditions. The resulting intermediate, l7cw-ethynyl1,4-dihydroestradiol-3-methyl ether (ll),” could readily be converted by weak acid treatment into the 3-keto-A5(i0) compound, norethynodrel (12),18~‘9or into the conjugated molecule, norethindrone (13), by treatment with stronger acid for a longer period of time. Dr. Carl Djerassi and his associates from Syntex had independently prepared norethindrone by an alternate process.20-22 I shall return to this work shortly, but I first want to continue with our synthesis of 19norhydrocortisone.
The selective reduction of l?“ethynyl-19-no~estosterone afforded 17-vinyl-19-nor-testosterone (14).23 Further selective reduction of the side chain afforded the 17-ethyl derivative (15).24,25Both 17-vinyl and f7ethyl-1Pnartestosterone were very active progestational agents and were considerably more active than the 17-ethynyl analogue. The 17-ethyl derivative, noreth~drolone~6,27 was also a very potent anabolic agent with relatively weak androgenicity, and was marketed in 1956 as the first anabolic agent with a favorable separation between protein building and virilizing properties. Anabolics have recently fallen into disrepute, largely because of the widespread abuse of these substances by athletes and would-be athletes. In the early 195Os,however, anabolics were considered a very promising area for research, and many laboratories were actively pursuing such compounds. There were high hopes that a selective anabolic agent would be useful in a variety of clinical conditions, such as growth retardation, osteoporosis, and wound healing, and as an aid to individuals recovering from debilitated states.
15
14
17-Vinyl-19-no~estosterone (14) was readily transformed via an allylic re~ngemeut into the 21-bromo (36) and then into the 21-acetoxy-17-ethy~dene derivative (17).28The latter compound was then converted by a Mischer-Schmidlin reaction into the 1Pnor analog of Reichstein’s compound S (18).29 This compound differs from the desired 19norhydrocortisone in that it does not have the IQ.5hydroxy group. To introduce this group by conventional chemical method01ogy would have been a difficult and lengthy undertaking. Therefore, we decided to attempt such an introduction biochemically.
16
t7
16
Oscar Hechter and his associates from the Worcester Foundation for Experimental Biology and Medicine had previously prepared hydrocortisone (19) by perfusing Reichstein’s compound S (28) through surviving mammalian adrenal glands,” We decided to ascertian if Hechter’s technique for the biochemist intr~uction of an ll@-hydroxy group in the normal steroid molecule could also be used with 19”nor steroids.
We perfused the 19-nor analogue of Reichstein’s compound S and were delighted that hydroxylation proceeded smoothly and in excellent yield, and that the primary product was the desired 19-~orhy~oco~iso~e (7). 19-Norhydrocortisone could also be obtained by introducing the 1lp-hydroxyl into the ethylidene comand then elaborating the cortisone side pound (17)r31,32 chain. We completed the synthesis of 19-norhydrocortisone late in 1952and were elated with the rapid success of our chemical effort. Unfortunately, we failed in our primary objective of developing a compound that would be superior to hydrocortisone as an antiinfl~” matory agent. Unlike hydrocortisone, the 19-nor analog had only weak ~tiin8ammatory activity. Even worse, 19-norhy~~o~isone was, su~~singly, an extremely potent salt-retaining agent. We realized that a substance with such a profile of biological activity would not be useful for the treatment of rheumatoid arthritis. Late in 1954, Zaffaroni, Ringold, Rosenkranz, Sondheimer, Thomas, and Djerassi from Syntex published a communication33 in which they also described a successful synthesis of 19-norhydro~o~isone, I have already described, in connection with the synthesis of 19-norhydroco~isoRe, the procedure we used for the preparation of norethynodrel and norethindrone. While our work was in progress, Djerassi and his associates from Syntex reported the synthesis of norethindrone in a preliminary communication*’ at a meeting of the American Chemical Society in Miiwaukee in April 1952. Norethindrone was patented by SyntexTn’and the detailed synthesis of this substance, considerably different from our own, was published in 1954 by the Syntex researchers.22 Norethyn~rel (l2) and norethindrone (13) are structurally similar and differ from each other only in the position of a double bond, Relatively minor structural differences in a steroid molecule are often accompanied by profound changes in biological activity. Norethyn~el and norethindrone are no exception to this generalization, and these two molecules display major differences in their profile of biological activityZ4 and in the manner by which they are metabolized.35-38 Norethindrone is the 19-nor analog of 17-ethynyltestosterone. It is also structurally similar to testosterone itself. Perhaps as a consequence of this structural feature, norethindrone possesses both progestational and, to a minor degree, androgenic activity. Norethynodrel also resembles ethynyltestosterone, and it, too, has orai progesteronelike activity. However, because the position of the doubfe bond in norethynodrel is between the A and B rings, this molecule is also structurally Steroids,
1992, vol. 57, December
627
Papers
related to ethynylestradiol (21), a potent estrogen. Thus, pure norethynodrel possesses both progestational activity and estrogenic activity and is devoid of androgenic effects. One of our early objectives was to develop a compound with progestational and estrogenie activity but which would be devoid of androgenicity.
HO 21
We were intrigued, when we first synthesized norethynodrel, as to whether the unique structural profile of this hybrid molecule would confer on this substance the anticipated and hoped for biological activity. With the aid of serendipity, the results far exceeded our expectations. Two of the early pivotal clinical studies with the orally effective progestins were crucial in the development of the oral contraceptives and related to our own overall effort in this area. Of the various compounds tested in the early studies in animals, three were found sufficiently promising to warrant a limited clinical trial. Two of these compounds, norethynodrel (12) and 17ethyl-19-nor-testosterone (15) were prepared in our laboratories, whereas the third compound, 17-ethynyl-19nortestosterone (13) was prepared by Djerassi and his associates at Syntex. The first clinical study with these compounds was initiated in December 1954 by Drs. Rock, Pincus, and Garcia.3g-4’ One or another of these three compounds was given orally and cyclically during three menstrual cycles to 50 women with idiopathic infertility. None of the women became pregnant during the treatment, and there appeared some evidence that fertility was enhanced after discontinuation of treatment. However, of special importance was the observation that all three compounds were effective ovulation inhibitors. This study was supported by grants from the Planned Parenthood Federation of America and from Searle. The frequency of spotting and bleeding in this study was high, and Rock suggested, based on an evaluation of endometrial biopsies, that estrogen be added to norethynodrel to aid in maintaining the endometrium. It was known that pure norethynodrel had significant estrogenic activity, but Rock postulated that better cycle control would be obtained with some added estrogen. Because of the encouraging results with ovulation inhibition in this initial clinical study, it was decided to conduct a field study in Puerto Rico on a larger number of women for a longer period of time. Norethynodrel administered with a small amount of the estrogen, mestranol, was chosen for this study. This compound was selected because norethynodrel appeared more active than the other two compounds in suppressing ovulation in the rabbit.6s42 In other studies,43 norethynodrel com628
Steroids,
1992, vol. 57, December
bined with a low dose of estrogen and given cyclically appeared to effectively regulate the menstrual cycle. This extended clinical study aided by a grant from Searle was a collaborative undertaking by Pincus from Shrewsbury; Rock and Garcia from Brookline; and Rice-Wray, Paniagua, Rodriguez, and Pedras from Puerto Rico.44 The above study, as well as many other studies initiated in Puerto Rico, Haiti, and the United States, demonstrated the almost complete contraceptive efficacy of norethynodrel when administered with a small amount of mestranol. The combination drug of 9.85 mg norethynodrel and 0.15 mg mestranol, trademarked Enovid, was approved in 1957 by the U.S. Food and Drug Administration (FDA) for the treatment of a variety of disorders associated with the menstrual cycle, and was introduced for such use by Searle in 1957. The FDA also granted approval at the same time for similar use for the single entity, norethindrone, which was marketed by Parke Davis and Co. as Norlutin under a license from Syntex. It should be pointed out that this single entity would not have been suitable for contraceptive use, whereas the formulation approved in 1957 for Enovid was the exact formulation subsequently approved and marketed for ovulation inhibition. Although Enovid was first approved for limited use in 1957, the era of oral contraception did not begin until 3 years later, in May 1960, when Enovid was approved by the FDA for the cyclic control of ovulation, and was immediately thereafter marketed for such use by Searle. Two years after Enovid was approved, the FDA also approved a combination of norethindrone and a small amount of mestranol for the cyclic control of ovulation. This combination was marketed as Ortho Novum early in 1963 by the Ortho division of Johnson & Johnson under a license from Syntex. This was 3 years after Enovid was marketed for such use. Because of its convenience, efficacy, and aesthetic appeal as a contraceptive, Enovid and similar preparations were widely accepted, and the number of women using such substances increased very rapidly; Enovid became known as “the pill.” In this review, I have touched only briefly on just a few of the highlights of our steroid research that related to Enovid. My involvement in this program was as a medicinal chemist, both a challenging and rewarding experience. In addition to those individuals whom I have already mentioned, special acknowledgment should be made to Leland Chinn and Leonard Nysted for chemical contributions, to Francis Saunders, Richard Edgren, and Richard Elton for endocrinological contributions, and to I. C. Winter and his associates for clinical contributions. In addition, the management of Searle deserves special commendation for its foresight and willingness to get involved and wholeheartedly support what appeared at the time, four decades ago, such a socially controversial, financially questionable, and scientifically challenging area as oral contraception.
Research at Searle on “The PW:
Cotton
Other steroid contributions So far I have commented primarily on the Searle research that related to Enovid and to several other 19-nor steroids. I would now like to comment briefly on some of the other early steroid research at our company. Ethynodiol diacetate (22) $5,46together with added estrogen, is marketed as Ovulen and Demulen, and represents Searle’s second-generation oral contraceptives .
I have already mentioned Nilevar (l!!), Searle’s first anabolic agent that possessed a marked separation between anabolic and androgenic activity. Anavar, 2-oxa17-methyldihydrotestosterone (23), was our secondgeneration anabolic agent. This compound, prepared by Pappo and Jung, 47displays an excellent separation between anabolic and androgenic activity.
OH a, .f
J$P 0
0
23
Pappo also prepareda a series of 2-oxa-4,9(10)dienes and 2-oxa-4,9(10),11-trienes (24), which are exceedingly potent anabolic androgenic substances. These interesting compounds have not been developed for marketing.
25
Aldactone is still an important drug. In addition to its antialdosterone antihypertensive properties, Aldactone also has antiandrogenic activity. As a result, this substance is potentially useful for the treatment of hirsutism, acne, and benign prostatic hypertrophy. Unfortunately, this compound has not been adequately explored in these areas. Counsell et aL5iprepared a series of aza cholesterols that displayed potent hypocholesterolemic activity. One of these substances, 22,25-diazacholesterol (26) appeared especially interesting and was evaluated in humans. This substance blocked the biosynthetic conversion of desmosterol into cholesterol and was effective in lowering cholesterol and serum triglyceride levels. Unfortunately, perhaps because of the elevated desmosterol levels, this diazacholesterol also caused reversible myotonia and was discontinued from further study. It is worth noting that this cholesterol analog has been used as a birth control pill for pigeons because it causes a thinning of the egg shell. Baran5*~53 prepared a series of 1l/3-methyl-1Pnor steroids and noted a marked increase in the basic hormonal properties of these molecules. One such compound, 1lP-methyl-17-acetoxy-IPnorprogesterone (27)) was licensed to CEVA and is marketed as a bovine estrus synchronizer. Several of these 1l-substituted steroids have considerable potential as estrogens or as contraceptives, but have not been developed for human use. n~“WH,,,
26
.w 24
Spironolactone (25)) marketed as Aldactone, was introduced in 1959. This compound, the first steroid antialdosterone antihypertensive agent, was prepared by Cella and Tweit” and was biologically evaluated by Kagawa, Sturtevant, and Van Armanso
27
In this review, I have touched on only the highlights of Searle steroid research during the 1950s and 1960s. That was an exciting and productive period, and I am thrilled to have played a role in that golden era of steroid research. References 1. Hench PS,
Kendall EC, et al. (1949). The effect of a hormone on the adrenal cortex (IFhydroxy-1 l-dehydro-corticosterone: Compound E) and on the pituitary adrenocorticotropic hormone. Proc St@Meet Mayo Clin 24181-197.
Steroids,
1992, vol.
57, December
629
Papers 2.
3.
4.
5.
6. I. 8. 9. 10.
11. 12. 13.
14. 15.
16. 17. 18. 19. 20. 21. 22.
23. 24. 25. 26. 27. 28.
630
Hench PS, Kendall EC, et al. (1950). Effects of cortisone acetate and pituitary ACTH on rheumatoid arthritis, rheumatic fever and certain other conditions. Arch intern Med 85:545-666. Colton FB, Nes WR, Van Dorp DA, Mason HL, Kendall EC Jr (1952). Steroids derived from bile acids. XIII. Introduction of the 17-hydroxy group in the partial synthesis of cortisone. J Biol Chem 194:235-245. Colton FB, Kendall EC Jr. (1952). Steroids derived from bile acids. XIV. Halogen and other derivatives of a Ar6-pregnene. J Biol Chem 194:247-260. Colton FB, Nes WR, Van Dorp DA, Mason HL, Kendall EC (September 1950). Abstracts of the 118th American Chemical Society Meeting, Chicago, IL, p. 20C. Drill VA. Rieael B (1958). Structural and hormonal activity of some new steroids.. Recent Prog Horm Res l&29-64. _ Ehrenstein M (1948). Synthesis of steroids of the progesterone series. Chem Rev 42457-489. Inhoffen HH, Hohlweg W (1938). New femaleglandularderivatives active per OS: 17-ethinylestradiol and pregnen-3-on-1701. Naturwissenschaften 26:%-107. Inhoffen HH, Hohlweg W, Serini A (1938). Untersuchungen in der Sexualhormone-Reihe. Ber. Deut. Chem. Ges. 7lr 1024-1032. Ehrenstein M (1944). Investigations on steroids. VII. Lower homologs of hormones of the pregnane series: lO-nor-ll-desoxy-corticosterone acetate and 10norprogesterone. J Org Chem 9~435-456. Birch AJ, Mukherji SM (1949). Reduction in dissolving metals. Part IV. Some applications in synthesis. J Chem Sot 253 l-2536. Birch AJ (1950). Hydroaromatic steroid hormones. Part I. loNortestosterone. J Chem Sot 367-368. Birch AJ, Smith H (1951). Hydroaromatic steroid hormones. Part II. Some hydrochrysene derivatives. J Chem Sot 1882-1888. Birch AJ (1950). Homocyclic compounds. Ann Rep Prog Chem 47:177-219. Wilds AL, Nelson N (1953). The facile synthesis of 19-nortestosterone and 19-norandrostenendione from esterone. J Am Chem Sot 75:5366-5369. Colton FB (1953). Estradienes. US. Patent 2,655,518. Colton FB (1954). Estadiene compounds. U.S. Patent 2,691,028. Colton FB (1955). 13-Methyl-17-ethynyl-17-hydroxy-1,2,3,4, 6.7.8.9.11.12.13.14,16.17-tetradecahydro15H-cyclopenta[a] phenanthren-3-&and its preparation. U.S. Patent 2,725,389. Chinn LJ, Colton FB (1965). Encyclopedia of Chemical Technology. Vol. 6. Wiley, New York. Djerassi C (1956). A4-lPNor-17a-ethinylandrosten-17@ol-3one and process. U.S. Patent 2,744,122. Djerassi C, Miramontes L, Rosenkranz G (1952). Abstracts of the 121st Meeting of the American Chemical Society, March 30-April 3, 1952, Milwaukee, WI, p. 185. Djerassi C, Miramonstes L, Rosenkranz G, Sondheimer F Jr (1954). Steroids. LIV. Synthesis of 19-nor-17or-ethynyltestosterone and 19-nor-17a-methyltestosterone. J Am Chem Sot 76~4092-4094. Colton FB (1958). 13-Methyl-17-hydroxy-17-vinyl-1,2,3,6, 7,8,9,10,11,12,13,14,16,17-tetradecahydro-l5H-cyclo~n~[a] phenanthren-3-one. U.S. Patent 2,838,529. Colton FB (1955). 17-Alkyl derivatives of 19nortestosterone. U.S. Patent 2,721,871. Colton FB, Nysted LN, Riegel B, Raymond AL Jr. (1957). 17Alkyl-19nortestosterones. J Am Chem Sot 79:1123-1127. Drill VA, Saunders FJ (1956). Hormones and the Aging Process. (Engle ET and Pincus G, eds.), Academic Press, New York, pp. 99-l 13. Saunders FJ, Drill VA (1956). The myotropic and androgenic effects of 17-ethyl-19nortestosterone and related compounds. Endocrinology, 58~567-572. Colton FB (1955). 17-(P-hydroxyethylidene)-13-methyl-1,2, 3,6,7,8,9,10,11,12,13,14,16,17 - tetradecahydro - 15H - cycle penta[a]phenanthren-3-ones and esters thereof. U.S. Patent 2,704,768.
Steroids,
1992, vol. 57, December
29.
30.
31.
32.
33.
34. 35.
36.
37.
38.
39.
40.
41.
42.
43. 44.
45. 46. 47. 48.
49. 50. 51. 52. 53.
Colton FB (1958). Derivatives of 13-methyl-17-hydroxy1,2,3,6,7,8,9,10,11,12,13,14,16,17-tetradecahydro-15H-cyclopenta[a]phenanthren-3-ones. U.S. Patent 2840,582. Hechter 0, Jacobsen RP, Jeanloz RW, Levy H, Marshall CW, Pincus G, Schenker VJ (1950). The bio-oxygenation of steroids at C-l 1. Arch Biochem Eiophys 25~457-459. Colton FB (1957). 1l-Oxygenated derivatives of 13-methyl-17hydroxy-17-(@hydroxyacetyl)-1 2 3 6 7 8 9 10,11,12,13,14, 1,,,,,, 16,17-tetradecahydro-lSH-cyclopenta[a]phenanthren-3-ones and esters thereof. U.S. Patent 2,802,015. Colton FB, Ralls JW (1954). 1I-Hydroxy-13-methyl-17(P-hydroxy-ethylidene)-1 ,2 ,3 36 ,7 t8 ,9 111,12,13,14,16,17-tetradecahydro-lSH-cyclopenta[a]phenanthren-3-one. U.S. Patent 2,694,080. Zalfaroni A, Ringold H, Rosenkranz G, Sondheimer F, Thomas GH, Djerassi C Jr. (1954). Steroids. LXIII. Synthesis of A4-19-norpregnene-l1/3-17a,21-triol-3,20-dione (lPnorhydrocortisone) and related 1Pnoradrenal hormones. J Am Chem Sot 76:6210-6211. Drill VA (1966). Oral Contraceptives. McGraw-Hill, New York, pp. 16-43. Arai K, Golab T, Layne DS, Pincus G (1%2). Metabolic fate of orally administered H3-norethylnodrel in rabbits. Endocrinology 71:639-648. Layne, DS, Golab T, Arai K, Pincus G (1%3). The metabolic fate of orally administered 3H-norethylnodrel and )H-norethindrone in humans. Biochem. Pharmacol U:905-911. Palmer KH, Smith DJS, Liepins L, Feierabend JF, Wall MA (1970). Metabolism of antifertility steroids. VI. Norethindrone. Pharmacologist 12:254. Cook CE, Twine ME, Tallent CR, Wall MA, Bressler RC Jr. (1972). Norethynodrel metabolites in human plasma and urine. Pharmacol. Exp Ther 183:197-205. Rock J, Pincus G, Garcia CR (1956). Effects of certain 19-nor steroids on the normal human menstrual cycle. Science w:891-893. Rock J, Garcia CR, Pincus G (1957). Synthetic progestins in the normal human menstrual cycle. Recent Prog Horm Res 13:323-346. Garcia CR, Pincus G, Rock J (1958). Effects of three 1Pnor steroids on human ovulation and menstruation. Am J Obstet Gynecol75:82-97. Pincus G (1956). Some effects of progesterone and related compounds upon the reproduction and early development in mammals. Acta Endocrinol [Suppl28] (Copenh) 18-36. Pincus G (1957). Proceedings of symposium on 19-norprogesrational steroids. Searle, Chicago. Pincus G, Rock J, Garcia CR, Rice-Wray E, Paniagua M, Rodriguez I, Pedras R (1958). Fertility control with oral medication. Am J Obstet Gynecol75:1333-1346. Colton FB (1958). Ill-Alkenyl and alkynyl derivatives of 4estrene-3,17-diol. U.S. Patent 2,843,609. Klimstra PD, Colton FB (1967). The synthesis of 3/3-hydroxyestr-4-en-17-one and 3P-hydroxyandrost-4-en-1Fone. Steroids 10~41l-424. Pappo R, Jung C (1%2). 2-Oxasteroids: a new class of biologically active compounds. Tetrahedron Lett., 365-371. Pappo R (1969). Novel chemistry and new biological activities of some 2-oxasteroids. Intra Sci Chem. Rep. 3, 105122. Cella J, Tweit RC (1959). Steroidal aldosterone blockers. II. J Org Chem 24:1109-1110. Kagawa CM, Sturtevant FM, Van Arman CG (1959). Pharmacology of a new steroid that blocks salt activity of aldosterone and desoxycorticosterone. J Pharm Exp Ther 126:123-130. Counsel1 RE, Klimstra PD, Ranney RE (1%5). Hypocholesterolemic agents. V. Isomeric azacholesterols. J Med Chem 8~45-48. Baran JS (1967). (Optionally 17-sydrocarbon-substituted) 11,13P-Dialkylgon4en-3-ones and esters corresponding. U.S. Patent 3,325,520. Baran JS (1%8). 17a-Alkynybalkenyl-11,13@dialkylgon5(10)-en-3-ones and esters thereof. U.S. Patent 3,377,366.
The announcement from the Mayo Clinic in 1949 of the dramatic effectiveness of cortisone in the treatment of rheumatoid arthritis stimulated tremendous interest in steroid chemistry, endocrinology, and related areas of medicine. Shortly thereafter, G. D. Searle & Co. initiated a major effort in steroid research, the objective of which was to discover better steroid drugs than those available at that time or steroids that could be used for conditions for which no compounds were previously available. This effort was remarkably successful and resulted in the introduction of several important pioneering drugs. These included norethandrolone, marketed in 1956 as Nilevar, the$rst anabolic agent with a favorable separation between protein building and virilization, and spironolactone, introduced in 19.59 as Aldactone, the$rst steroid antialdosterone antihypertensive agent. Of special importance was the research that culminated in the discovery ofEnovid. This substance, a combination oftheprogestin norethynodrel and the estrogen mestranol was jirst approved in 1957 for the treatment of a variety of disorders associated with the menstrual cycle. The era of oral contraception began in May 1960, when Enovid was approved by the Food and Drug Administration for ovulation inhibition, and was immediately thereafter introduced for such use. (Steroids 57624-630, 1992)
Keywords:
steroids; Searle; Enovid; progesterone;
ovulation inhibition; birth control pill; oral contraceptive
Introduction I would like to describe the early steroid research at G. D. Searle & Co., with emphasis on the research that led to the discovery and development of the first oral contraceptive, Enovid, a substance that became popularly known as “the Pill.” The announcement from the Mayo Clinic in 1949 by Drs. Edward C. Kendall, Philip Hench and their associates’s2 of cortisone’s dramatic effectiveness in the treatment of rheumatoid arthritis touched off one of the greatest bursts of excitement in the entire history of drug therapy. Cortisone was acclaimed as one of the most significant discoveries of the generation. This discovery resulted in the 1950 award of the Nobel Prize in Physiology and Medicine to Drs. Kendall and Hench from the Mayo Clinic and to Dr. Tadeus Reichstein from Switzerland. I completed the requirements for the Ph.D. degree in organic chemistry from the University of Chicago in 1949, at the time when these dramatic results with cortisone were beginning to come out from the Mayo Clinic, and was extremely fortunate to have been invited by Kendall to join his group at the Mayo Clinic Address reprint requests Evanston, IL 60203.
624
Steroids,
to Dr. Frank B. Colton,
1992, vol. 57, December
39dl Lyons,
during this exciting period of steroid research. For a new Ph.D., the privilege to work at the Mayo Clinic at such an opportune time, on such an important problem, and with a scientist such as Kendall was indeed a dream come true. My assigned task was to develop an alternate and hopefully superior method to those available at that time for the introduction of the 17-hydroxyl group in the partial synthesis of cortisone. We were indeed fortunate to have succeeded in this objective.3-5 Understandably, the discovery of the exciting potential of cortisone stimulated tremendous interest in steroid chemistry, endocrinology, and related areas of medicine, and practically every leading pharmaceutical company and many research and medical centers throughout the world began active programs in these areas. G. D. Searle & Co., a small ethical pharmaceutical house located in Skokie, a suburb of Chicago, Illinois, also decided to get involved in steroid research. The total annual sales of Searle at that time were about $20,000,000. Although the company had a limited product line, most of its products were highly innovative and were developed as a result of its own research. One such innovative drug was Dramamine. This substance, the first antimotion sickness pill, was introduced in 1949 and still retains the dominant position in this field.
0 1992 Butterworth-Heinemann
Research at Searle on “The Pill”: Colton
Dr. Albert L, Raymond, the Vice-President of Research and Development at Searle, was convinced that steroids represented a promising growth area with great potential in medicine and he initiated steps to get the company involved in steroid research on a significant scale. In 1951 he hired Dr. Byron Riegel, a professor of chemistry from Northwestern University with research experience in steroids, to become Director of Chemical Research and Development. He also hired other senior scientists, both chemists and biologists, with experience in steroids. I was fortunate to have been invited to join this group of excellent scientists in 1951. Earlier, Raymond also succeeded in attracting as a consultant Dr. Gregory Pincus, the well known reproductive physiologist who was Director of the Worcester Foundation for Experimental Biology and Medicine. The overall objective of our steroid program was to discover, develop, and introduce into clinical use better steroid drugs than those available at the time and/or steroids that would be useful in conditions for which no compounds were previously available.6 Our pioneering steroid effort was, indeed, remarkably successful in its primary objective, and several important breakthrough drugs were developed and marketed. These included Nilevar, introduced in 1956, the first anabolic agent that had a favorable separation between its protein building and virilizing properties, and Aldactone, introduced in 1959, the first steroid antialdosterone antihypertensive agent. Of special importance, however, was the research which culminated in the introduction of Enovid, the first oral contraceptive _ It is now 40 years since norethynodrel, the progestin component of Enovid, was first synthesized. The preparation of norethynodrel and various related compounds was part of a planned program undertaken in the hope of developing an orally effective compound that would have progestational activity, inhibit ovulation, and would produce a reversible antife~ility effect in experimental animals. It was also our objective that such a compound should not have androgenic activity or other undesirable endocrine effects and no untoward toxicity in animal studies. It had been known since the beginning of this century that, in animal studies, extracts of the corpus luteum were capable of inhibiting ovulation. Shortly after pure progesterone (1)became available, Makepeace and his associates from the University of Pennsylvania showed that this substance, by injection, inhibits ovulation in the rabbit. In addition to ovulation inhibition, progesterone also has other impo~ant physiologic~ properties. For example, progesterone is necessary during pregnancy to prevent the spontaneous abortion of the implanted fertilized ovum. It is because of this property that progesterone has been referred to as the pregnancy hormone. Paradoxically, then, progesterone, at least in theory, can be used for both contraceptive and proceptive purposes. Despite the key role of endogenous progesterone in fertility control, the use of this natural hormone to
enhance fertility or for contraceptive purposes was not considered practical. For example, progesterone has very low activity when taken orally and, when given intramuscularly, it often causes a severe reaction at the site of injection. In an attempt to obtain molecules with greater effectiveness, numerous structural modifications of the progesterone molecule were prepared by early researchers and were investigated for progesteronelike activity. Unfortunately, most of these modifications resulted in either complete loss or marked diminution of biological activity.’ In view of the very high degree of structural specificity required for physiological activity, as shown by the lack of activity of so many closely related derivatives of progesterone, it was therefore completely unexpected that 17-ethynyltestosterone (2), a substance structurally different from progesterone but that instead resembles the male hormone testosterone (3), possessed progestational activity on oral administ~tion. Although the oral potency of this material was low, and the compound, as expected, had appreciable androgenic activity, this compound did possess considerably higher oral progestational activity than natural progesterone and was marketed in Europe in 1941 as ethisterone, a progestational agent for the treatment of certain female disorders. This compound was prepared in 1937 by Inhoffen and associates8t9 The finding of appreciable oral progestational activity for ethisterone was an important observation, which guided subsequent work in the 1Pnor steroid area.
I
2
3
In 1944 Professor Maximili~ Ehrenstein from the University of Pennsylvania succeeded in the conversion of the cardiac aglycone, strophanthidin (4), in a 0.07% yield into a resin that he believed to be 19norprogestone (5).” Ehrenstein’s compound appeared impure and its structure was uncertain. Nevertheless, this compound was at least as potent a progestational agent in the rabbit, by injection, as natural progesterone. This finding of such high progestational activity of Ehrenstein’s compound was of special significance, because it was known that relatively minor structural changes in the progesterone molecule were often accompanied by marked reduction or complete elimination of biological activity. Such high activity of a 19-nor steroid was an important structural clue in the discovery of oral contraceptives.
Steroids, 1992, vol. 57, December
625
Papers
In 1949 Birch and Mukherji” from England described a method for the conversion of estradiol into a 1,4-dihydro steroid. Shortly thereafter, Birch” described the transformation of this 1,4-dihydro derivative into 19-nortestosterone (6). Birch also indicated that his objective was to prepare additional 19-nor steroids from estrone to ascertain whether the expenditure of effort necessary for the complete synthesis of such 19-nor analogues was justified. In 1951, Birch and his student, Herschel Smith,13 stated that 19-nortestosterone possessed appreciable androgenic activity. This activity was reported elsewhere to be considerably less than testosterone. “1’5 on
LP n
0
Shortly after the publications by Birch, Professor Alfred Wilds and his student, Norman Nelson from the University of Wisconsin, improved on the Birch method of reduction.15 Wilds informed Jack Ralls, one of his former students who joined our steroid group, about his improved Birch procedure before publication. We and, I understand, the Syntex researchers used the Wilds-Nelson modification of the Birch reduction in the early studies with 19-nor steroids. To recapitulate, the observation of the unexpected oral progestational activity of 17-ethynyltestosterone and the high parenteral progestational activity of Ehrenstein’s “19-not-progesterone” suggested to us at Searle and, independently, to the Syntex investigators that the combination of these structural clues might afford a clinically useful new class of compounds. Furthermore, the synthetic advances of Birch and of Wilds and Nelson afforded the means for the preparation of such molecules.
Norethynodrel, Enovid, Norethandrolone, 19-norhydrocortisone One of the early objectives of our steroid research was to study the effects of various structural parameters on the biological properties of steroid hormones in the hope of improving the therapeutic effectiveness of these substances.6 The 19-nor steroids appeared to offer promise as potentially useful therapeutic agents and we decided to prepare several key compounds in this area. We were not interested in potency alone but hoped that certain of these compounds would have a better profile of biological activity than the natural compounds. We were aware of the interest in 19-nor steroids by other laboratories, but we nevertheless decided to enter this competitive area because we were confident we could make a significant contribution. Improvement on the biological profile of cortisone or hydrocortisone was one of our objectives in the antiinflammatory area. We believed that the 19-nor an626
Steroids,
1992, vol. 57, December
alog of hydrocortisone (7) was a promising candidate in this regard, and we devised a synthesis that we believed was unique and that incorporated both chemical and biochemical methodology. Furthermore, our synthetic approach for 1Pnorhydrocortisone was such that it could readily be adapted for the preparation of other potentially valuable 19-nor steroids in the progestational, estrogenic, anabolic, and antihypertensive categories. These areas were of considerable interest to us and were on a comparable priority with our interest in the antiinflammatory area. We developed in-house testing capability for the biological evaluation of such compounds. In addition we submitted selected compounds to Pincus and Chang of the Worcester Foundation for Experimental Biology and Medicine for screening for ovulation inhibition in the rabbit.
The 3-methyl ether of estradiol (8) was reduced by the Wilds-Nelson modification of the Birch reduction” to the dihydro enol ether (9).
a
9
10
Careful Oppenauer oxidation of this sensitive enol etheri afforded a good yield of the 3-methyl ether of 1,4_dihydroestrone (10). This compound was a key intermediate for the synthesis of many of our Asoo) and 19-nor-A4 steroids. The 17-ethynyl group was introduced by reacting the 17-keto derivative with acetylene under basic conditions. The resulting intermediate, l7cw-ethynyl1,4-dihydroestradiol-3-methyl ether (ll),” could readily be converted by weak acid treatment into the 3-keto-A5(i0) compound, norethynodrel (12),18~‘9or into the conjugated molecule, norethindrone (13), by treatment with stronger acid for a longer period of time. Dr. Carl Djerassi and his associates from Syntex had independently prepared norethindrone by an alternate process.20-22 I shall return to this work shortly, but I first want to continue with our synthesis of 19norhydrocortisone.
The selective reduction of l?“ethynyl-19-no~estosterone afforded 17-vinyl-19-nor-testosterone (14).23 Further selective reduction of the side chain afforded the 17-ethyl derivative (15).24,25Both 17-vinyl and f7ethyl-1Pnartestosterone were very active progestational agents and were considerably more active than the 17-ethynyl analogue. The 17-ethyl derivative, noreth~drolone~6,27 was also a very potent anabolic agent with relatively weak androgenicity, and was marketed in 1956 as the first anabolic agent with a favorable separation between protein building and virilizing properties. Anabolics have recently fallen into disrepute, largely because of the widespread abuse of these substances by athletes and would-be athletes. In the early 195Os,however, anabolics were considered a very promising area for research, and many laboratories were actively pursuing such compounds. There were high hopes that a selective anabolic agent would be useful in a variety of clinical conditions, such as growth retardation, osteoporosis, and wound healing, and as an aid to individuals recovering from debilitated states.
15
14
17-Vinyl-19-no~estosterone (14) was readily transformed via an allylic re~ngemeut into the 21-bromo (36) and then into the 21-acetoxy-17-ethy~dene derivative (17).28The latter compound was then converted by a Mischer-Schmidlin reaction into the 1Pnor analog of Reichstein’s compound S (18).29 This compound differs from the desired 19norhydrocortisone in that it does not have the IQ.5hydroxy group. To introduce this group by conventional chemical method01ogy would have been a difficult and lengthy undertaking. Therefore, we decided to attempt such an introduction biochemically.
16
t7
16
Oscar Hechter and his associates from the Worcester Foundation for Experimental Biology and Medicine had previously prepared hydrocortisone (19) by perfusing Reichstein’s compound S (28) through surviving mammalian adrenal glands,” We decided to ascertian if Hechter’s technique for the biochemist intr~uction of an ll@-hydroxy group in the normal steroid molecule could also be used with 19”nor steroids.
We perfused the 19-nor analogue of Reichstein’s compound S and were delighted that hydroxylation proceeded smoothly and in excellent yield, and that the primary product was the desired 19-~orhy~oco~iso~e (7). 19-Norhydrocortisone could also be obtained by introducing the 1lp-hydroxyl into the ethylidene comand then elaborating the cortisone side pound (17)r31,32 chain. We completed the synthesis of 19-norhydrocortisone late in 1952and were elated with the rapid success of our chemical effort. Unfortunately, we failed in our primary objective of developing a compound that would be superior to hydrocortisone as an antiinfl~” matory agent. Unlike hydrocortisone, the 19-nor analog had only weak ~tiin8ammatory activity. Even worse, 19-norhy~~o~isone was, su~~singly, an extremely potent salt-retaining agent. We realized that a substance with such a profile of biological activity would not be useful for the treatment of rheumatoid arthritis. Late in 1954, Zaffaroni, Ringold, Rosenkranz, Sondheimer, Thomas, and Djerassi from Syntex published a communication33 in which they also described a successful synthesis of 19-norhydro~o~isone, I have already described, in connection with the synthesis of 19-norhydroco~isoRe, the procedure we used for the preparation of norethynodrel and norethindrone. While our work was in progress, Djerassi and his associates from Syntex reported the synthesis of norethindrone in a preliminary communication*’ at a meeting of the American Chemical Society in Miiwaukee in April 1952. Norethindrone was patented by SyntexTn’and the detailed synthesis of this substance, considerably different from our own, was published in 1954 by the Syntex researchers.22 Norethyn~rel (l2) and norethindrone (13) are structurally similar and differ from each other only in the position of a double bond, Relatively minor structural differences in a steroid molecule are often accompanied by profound changes in biological activity. Norethyn~el and norethindrone are no exception to this generalization, and these two molecules display major differences in their profile of biological activityZ4 and in the manner by which they are metabolized.35-38 Norethindrone is the 19-nor analog of 17-ethynyltestosterone. It is also structurally similar to testosterone itself. Perhaps as a consequence of this structural feature, norethindrone possesses both progestational and, to a minor degree, androgenic activity. Norethynodrel also resembles ethynyltestosterone, and it, too, has orai progesteronelike activity. However, because the position of the doubfe bond in norethynodrel is between the A and B rings, this molecule is also structurally Steroids,
1992, vol. 57, December
627
Papers
related to ethynylestradiol (21), a potent estrogen. Thus, pure norethynodrel possesses both progestational activity and estrogenic activity and is devoid of androgenic effects. One of our early objectives was to develop a compound with progestational and estrogenie activity but which would be devoid of androgenicity.
HO 21
We were intrigued, when we first synthesized norethynodrel, as to whether the unique structural profile of this hybrid molecule would confer on this substance the anticipated and hoped for biological activity. With the aid of serendipity, the results far exceeded our expectations. Two of the early pivotal clinical studies with the orally effective progestins were crucial in the development of the oral contraceptives and related to our own overall effort in this area. Of the various compounds tested in the early studies in animals, three were found sufficiently promising to warrant a limited clinical trial. Two of these compounds, norethynodrel (12) and 17ethyl-19-nor-testosterone (15) were prepared in our laboratories, whereas the third compound, 17-ethynyl-19nortestosterone (13) was prepared by Djerassi and his associates at Syntex. The first clinical study with these compounds was initiated in December 1954 by Drs. Rock, Pincus, and Garcia.3g-4’ One or another of these three compounds was given orally and cyclically during three menstrual cycles to 50 women with idiopathic infertility. None of the women became pregnant during the treatment, and there appeared some evidence that fertility was enhanced after discontinuation of treatment. However, of special importance was the observation that all three compounds were effective ovulation inhibitors. This study was supported by grants from the Planned Parenthood Federation of America and from Searle. The frequency of spotting and bleeding in this study was high, and Rock suggested, based on an evaluation of endometrial biopsies, that estrogen be added to norethynodrel to aid in maintaining the endometrium. It was known that pure norethynodrel had significant estrogenic activity, but Rock postulated that better cycle control would be obtained with some added estrogen. Because of the encouraging results with ovulation inhibition in this initial clinical study, it was decided to conduct a field study in Puerto Rico on a larger number of women for a longer period of time. Norethynodrel administered with a small amount of the estrogen, mestranol, was chosen for this study. This compound was selected because norethynodrel appeared more active than the other two compounds in suppressing ovulation in the rabbit.6s42 In other studies,43 norethynodrel com628
Steroids,
1992, vol. 57, December
bined with a low dose of estrogen and given cyclically appeared to effectively regulate the menstrual cycle. This extended clinical study aided by a grant from Searle was a collaborative undertaking by Pincus from Shrewsbury; Rock and Garcia from Brookline; and Rice-Wray, Paniagua, Rodriguez, and Pedras from Puerto Rico.44 The above study, as well as many other studies initiated in Puerto Rico, Haiti, and the United States, demonstrated the almost complete contraceptive efficacy of norethynodrel when administered with a small amount of mestranol. The combination drug of 9.85 mg norethynodrel and 0.15 mg mestranol, trademarked Enovid, was approved in 1957 by the U.S. Food and Drug Administration (FDA) for the treatment of a variety of disorders associated with the menstrual cycle, and was introduced for such use by Searle in 1957. The FDA also granted approval at the same time for similar use for the single entity, norethindrone, which was marketed by Parke Davis and Co. as Norlutin under a license from Syntex. It should be pointed out that this single entity would not have been suitable for contraceptive use, whereas the formulation approved in 1957 for Enovid was the exact formulation subsequently approved and marketed for ovulation inhibition. Although Enovid was first approved for limited use in 1957, the era of oral contraception did not begin until 3 years later, in May 1960, when Enovid was approved by the FDA for the cyclic control of ovulation, and was immediately thereafter marketed for such use by Searle. Two years after Enovid was approved, the FDA also approved a combination of norethindrone and a small amount of mestranol for the cyclic control of ovulation. This combination was marketed as Ortho Novum early in 1963 by the Ortho division of Johnson & Johnson under a license from Syntex. This was 3 years after Enovid was marketed for such use. Because of its convenience, efficacy, and aesthetic appeal as a contraceptive, Enovid and similar preparations were widely accepted, and the number of women using such substances increased very rapidly; Enovid became known as “the pill.” In this review, I have touched only briefly on just a few of the highlights of our steroid research that related to Enovid. My involvement in this program was as a medicinal chemist, both a challenging and rewarding experience. In addition to those individuals whom I have already mentioned, special acknowledgment should be made to Leland Chinn and Leonard Nysted for chemical contributions, to Francis Saunders, Richard Edgren, and Richard Elton for endocrinological contributions, and to I. C. Winter and his associates for clinical contributions. In addition, the management of Searle deserves special commendation for its foresight and willingness to get involved and wholeheartedly support what appeared at the time, four decades ago, such a socially controversial, financially questionable, and scientifically challenging area as oral contraception.
Research at Searle on “The PW:
Cotton
Other steroid contributions So far I have commented primarily on the Searle research that related to Enovid and to several other 19-nor steroids. I would now like to comment briefly on some of the other early steroid research at our company. Ethynodiol diacetate (22) $5,46together with added estrogen, is marketed as Ovulen and Demulen, and represents Searle’s second-generation oral contraceptives .
I have already mentioned Nilevar (l!!), Searle’s first anabolic agent that possessed a marked separation between anabolic and androgenic activity. Anavar, 2-oxa17-methyldihydrotestosterone (23), was our secondgeneration anabolic agent. This compound, prepared by Pappo and Jung, 47displays an excellent separation between anabolic and androgenic activity.
OH a, .f
J$P 0
0
23
Pappo also prepareda a series of 2-oxa-4,9(10)dienes and 2-oxa-4,9(10),11-trienes (24), which are exceedingly potent anabolic androgenic substances. These interesting compounds have not been developed for marketing.
25
Aldactone is still an important drug. In addition to its antialdosterone antihypertensive properties, Aldactone also has antiandrogenic activity. As a result, this substance is potentially useful for the treatment of hirsutism, acne, and benign prostatic hypertrophy. Unfortunately, this compound has not been adequately explored in these areas. Counsell et aL5iprepared a series of aza cholesterols that displayed potent hypocholesterolemic activity. One of these substances, 22,25-diazacholesterol (26) appeared especially interesting and was evaluated in humans. This substance blocked the biosynthetic conversion of desmosterol into cholesterol and was effective in lowering cholesterol and serum triglyceride levels. Unfortunately, perhaps because of the elevated desmosterol levels, this diazacholesterol also caused reversible myotonia and was discontinued from further study. It is worth noting that this cholesterol analog has been used as a birth control pill for pigeons because it causes a thinning of the egg shell. Baran5*~53 prepared a series of 1l/3-methyl-1Pnor steroids and noted a marked increase in the basic hormonal properties of these molecules. One such compound, 1lP-methyl-17-acetoxy-IPnorprogesterone (27)) was licensed to CEVA and is marketed as a bovine estrus synchronizer. Several of these 1l-substituted steroids have considerable potential as estrogens or as contraceptives, but have not been developed for human use. n~“WH,,,
26
.w 24
Spironolactone (25)) marketed as Aldactone, was introduced in 1959. This compound, the first steroid antialdosterone antihypertensive agent, was prepared by Cella and Tweit” and was biologically evaluated by Kagawa, Sturtevant, and Van Armanso
27
In this review, I have touched on only the highlights of Searle steroid research during the 1950s and 1960s. That was an exciting and productive period, and I am thrilled to have played a role in that golden era of steroid research. References 1. Hench PS,
Kendall EC, et al. (1949). The effect of a hormone on the adrenal cortex (IFhydroxy-1 l-dehydro-corticosterone: Compound E) and on the pituitary adrenocorticotropic hormone. Proc St@Meet Mayo Clin 24181-197.
Steroids,
1992, vol.
57, December
629
Papers 2.
3.
4.
5.
6. I. 8. 9. 10.
11. 12. 13.
14. 15.
16. 17. 18. 19. 20. 21. 22.
23. 24. 25. 26. 27. 28.
630
Hench PS, Kendall EC, et al. (1950). Effects of cortisone acetate and pituitary ACTH on rheumatoid arthritis, rheumatic fever and certain other conditions. Arch intern Med 85:545-666. Colton FB, Nes WR, Van Dorp DA, Mason HL, Kendall EC Jr (1952). Steroids derived from bile acids. XIII. Introduction of the 17-hydroxy group in the partial synthesis of cortisone. J Biol Chem 194:235-245. Colton FB, Kendall EC Jr. (1952). Steroids derived from bile acids. XIV. Halogen and other derivatives of a Ar6-pregnene. J Biol Chem 194:247-260. Colton FB, Nes WR, Van Dorp DA, Mason HL, Kendall EC (September 1950). Abstracts of the 118th American Chemical Society Meeting, Chicago, IL, p. 20C. Drill VA. Rieael B (1958). Structural and hormonal activity of some new steroids.. Recent Prog Horm Res l&29-64. _ Ehrenstein M (1948). Synthesis of steroids of the progesterone series. Chem Rev 42457-489. Inhoffen HH, Hohlweg W (1938). New femaleglandularderivatives active per OS: 17-ethinylestradiol and pregnen-3-on-1701. Naturwissenschaften 26:%-107. Inhoffen HH, Hohlweg W, Serini A (1938). Untersuchungen in der Sexualhormone-Reihe. Ber. Deut. Chem. Ges. 7lr 1024-1032. Ehrenstein M (1944). Investigations on steroids. VII. Lower homologs of hormones of the pregnane series: lO-nor-ll-desoxy-corticosterone acetate and 10norprogesterone. J Org Chem 9~435-456. Birch AJ, Mukherji SM (1949). Reduction in dissolving metals. Part IV. Some applications in synthesis. J Chem Sot 253 l-2536. Birch AJ (1950). Hydroaromatic steroid hormones. Part I. loNortestosterone. J Chem Sot 367-368. Birch AJ, Smith H (1951). Hydroaromatic steroid hormones. Part II. Some hydrochrysene derivatives. J Chem Sot 1882-1888. Birch AJ (1950). Homocyclic compounds. Ann Rep Prog Chem 47:177-219. Wilds AL, Nelson N (1953). The facile synthesis of 19-nortestosterone and 19-norandrostenendione from esterone. J Am Chem Sot 75:5366-5369. Colton FB (1953). Estradienes. US. Patent 2,655,518. Colton FB (1954). Estadiene compounds. U.S. Patent 2,691,028. Colton FB (1955). 13-Methyl-17-ethynyl-17-hydroxy-1,2,3,4, 6.7.8.9.11.12.13.14,16.17-tetradecahydro15H-cyclopenta[a] phenanthren-3-&and its preparation. U.S. Patent 2,725,389. Chinn LJ, Colton FB (1965). Encyclopedia of Chemical Technology. Vol. 6. Wiley, New York. Djerassi C (1956). A4-lPNor-17a-ethinylandrosten-17@ol-3one and process. U.S. Patent 2,744,122. Djerassi C, Miramontes L, Rosenkranz G (1952). Abstracts of the 121st Meeting of the American Chemical Society, March 30-April 3, 1952, Milwaukee, WI, p. 185. Djerassi C, Miramonstes L, Rosenkranz G, Sondheimer F Jr (1954). Steroids. LIV. Synthesis of 19-nor-17or-ethynyltestosterone and 19-nor-17a-methyltestosterone. J Am Chem Sot 76~4092-4094. Colton FB (1958). 13-Methyl-17-hydroxy-17-vinyl-1,2,3,6, 7,8,9,10,11,12,13,14,16,17-tetradecahydro-l5H-cyclo~n~[a] phenanthren-3-one. U.S. Patent 2,838,529. Colton FB (1955). 17-Alkyl derivatives of 19nortestosterone. U.S. Patent 2,721,871. Colton FB, Nysted LN, Riegel B, Raymond AL Jr. (1957). 17Alkyl-19nortestosterones. J Am Chem Sot 79:1123-1127. Drill VA, Saunders FJ (1956). Hormones and the Aging Process. (Engle ET and Pincus G, eds.), Academic Press, New York, pp. 99-l 13. Saunders FJ, Drill VA (1956). The myotropic and androgenic effects of 17-ethyl-19nortestosterone and related compounds. Endocrinology, 58~567-572. Colton FB (1955). 17-(P-hydroxyethylidene)-13-methyl-1,2, 3,6,7,8,9,10,11,12,13,14,16,17 - tetradecahydro - 15H - cycle penta[a]phenanthren-3-ones and esters thereof. U.S. Patent 2,704,768.
Steroids,
1992, vol. 57, December
29.
30.
31.
32.
33.
34. 35.
36.
37.
38.
39.
40.
41.
42.
43. 44.
45. 46. 47. 48.
49. 50. 51. 52. 53.
Colton FB (1958). Derivatives of 13-methyl-17-hydroxy1,2,3,6,7,8,9,10,11,12,13,14,16,17-tetradecahydro-15H-cyclopenta[a]phenanthren-3-ones. U.S. Patent 2840,582. Hechter 0, Jacobsen RP, Jeanloz RW, Levy H, Marshall CW, Pincus G, Schenker VJ (1950). The bio-oxygenation of steroids at C-l 1. Arch Biochem Eiophys 25~457-459. Colton FB (1957). 1l-Oxygenated derivatives of 13-methyl-17hydroxy-17-(@hydroxyacetyl)-1 2 3 6 7 8 9 10,11,12,13,14, 1,,,,,, 16,17-tetradecahydro-lSH-cyclopenta[a]phenanthren-3-ones and esters thereof. U.S. Patent 2,802,015. Colton FB, Ralls JW (1954). 1I-Hydroxy-13-methyl-17(P-hydroxy-ethylidene)-1 ,2 ,3 36 ,7 t8 ,9 111,12,13,14,16,17-tetradecahydro-lSH-cyclopenta[a]phenanthren-3-one. U.S. Patent 2,694,080. Zalfaroni A, Ringold H, Rosenkranz G, Sondheimer F, Thomas GH, Djerassi C Jr. (1954). Steroids. LXIII. Synthesis of A4-19-norpregnene-l1/3-17a,21-triol-3,20-dione (lPnorhydrocortisone) and related 1Pnoradrenal hormones. J Am Chem Sot 76:6210-6211. Drill VA (1966). Oral Contraceptives. McGraw-Hill, New York, pp. 16-43. Arai K, Golab T, Layne DS, Pincus G (1%2). Metabolic fate of orally administered H3-norethylnodrel in rabbits. Endocrinology 71:639-648. Layne, DS, Golab T, Arai K, Pincus G (1%3). The metabolic fate of orally administered 3H-norethylnodrel and )H-norethindrone in humans. Biochem. Pharmacol U:905-911. Palmer KH, Smith DJS, Liepins L, Feierabend JF, Wall MA (1970). Metabolism of antifertility steroids. VI. Norethindrone. Pharmacologist 12:254. Cook CE, Twine ME, Tallent CR, Wall MA, Bressler RC Jr. (1972). Norethynodrel metabolites in human plasma and urine. Pharmacol. Exp Ther 183:197-205. Rock J, Pincus G, Garcia CR (1956). Effects of certain 19-nor steroids on the normal human menstrual cycle. Science w:891-893. Rock J, Garcia CR, Pincus G (1957). Synthetic progestins in the normal human menstrual cycle. Recent Prog Horm Res 13:323-346. Garcia CR, Pincus G, Rock J (1958). Effects of three 1Pnor steroids on human ovulation and menstruation. Am J Obstet Gynecol75:82-97. Pincus G (1956). Some effects of progesterone and related compounds upon the reproduction and early development in mammals. Acta Endocrinol [Suppl28] (Copenh) 18-36. Pincus G (1957). Proceedings of symposium on 19-norprogesrational steroids. Searle, Chicago. Pincus G, Rock J, Garcia CR, Rice-Wray E, Paniagua M, Rodriguez I, Pedras R (1958). Fertility control with oral medication. Am J Obstet Gynecol75:1333-1346. Colton FB (1958). Ill-Alkenyl and alkynyl derivatives of 4estrene-3,17-diol. U.S. Patent 2,843,609. Klimstra PD, Colton FB (1967). The synthesis of 3/3-hydroxyestr-4-en-17-one and 3P-hydroxyandrost-4-en-1Fone. Steroids 10~41l-424. Pappo R, Jung C (1%2). 2-Oxasteroids: a new class of biologically active compounds. Tetrahedron Lett., 365-371. Pappo R (1969). Novel chemistry and new biological activities of some 2-oxasteroids. Intra Sci Chem. Rep. 3, 105122. Cella J, Tweit RC (1959). Steroidal aldosterone blockers. II. J Org Chem 24:1109-1110. Kagawa CM, Sturtevant FM, Van Arman CG (1959). Pharmacology of a new steroid that blocks salt activity of aldosterone and desoxycorticosterone. J Pharm Exp Ther 126:123-130. Counsel1 RE, Klimstra PD, Ranney RE (1%5). Hypocholesterolemic agents. V. Isomeric azacholesterols. J Med Chem 8~45-48. Baran JS (1967). (Optionally 17-sydrocarbon-substituted) 11,13P-Dialkylgon4en-3-ones and esters corresponding. U.S. Patent 3,325,520. Baran JS (1%8). 17a-Alkynybalkenyl-11,13@dialkylgon5(10)-en-3-ones and esters thereof. U.S. Patent 3,377,366.
