Effects of lovastatin in diabetic patients
treated with chlorpropamide Patients with noninsulin dependent diabetes mellitus (NIDDM) have a higher risk of atherosclerotic cardiovascular disease than nondiabetic subjects. In seven patients with both hypercholesterolemia and NIDDM controlled by chlorpropamide, lovastatin (20 mg b.i.d. for 6 weeks) lowered low-density lipoprotein cholesterol by 28%, total cholesterol by 24%, and apolipoprotein B by 24%. Lovastatin levels for a 4-hour period (measured as 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitory activity) were similar to those measured previously in nondiabetic patients. Lovastatin did not alter chlorpropamide kinetics or glycemic profiles. No patient had an elevation in serum transaminases or creatinine phosphokinase, and no patient had any other laboratory or clinical drug-related adverse experience during the study. Lovastatin was as effective in reducing low-density lipoprotein cholesterol in patients with NIDDM as in nondiabetic subjects. Diabetic control was unaltered, and no evidence of alteration in lovastatin or chlorpropamide blood levels was noted. (CLIN PHARMACOL THER 1990;48:467-72.)
Brian F. Johnson, MD, Patrice LaBelle, MD, John Wilson, PhD, Judy Allan, BS, Robert V. Zupkis, PhD, and Philip D. Ronca, BS Worcester, Mass., and West Point, Pa. Patients with noninsulin dependent diabetes mellitus (NIDDM) have a higher risk of atherosclerotic cardiovascular disease than that of nondiabetic patients.' It is probable that the lipid abnormalities found in these patients play a role in the development of their atherosclerosis. It has been shown that lovastatin can improve some of the lipid abnormalities in diabetic patients' to an extent similar to those in nondiabetic subjects with lipid abnormalities. The purpose of our study was to confirm the effects of lovastatin in hypercholesterolemic patients with NIDDM and to determine whether the drug has any important effect on control of diabetes. A related objective was to determine whether there was any interaction between lovastatin and chlorpropamide, an oral agent commonly used to treat this type of diabetic patient.
METHODS The main criteria for selection of patients for the study were the presence of NIDDM under reasonable control with stable doses of chlorpropamide and persistent elevation of plasma total cholesterol to levels From the Division of Clinical Pharmacology, University of Massachusetts Medical Center, Worcester, and Merck Sharp & Dohme Research Laboratories, West Point. Received for publication March 30, 1990; accepted July 26, 1990. Reprint requests: Brian F. Johnson, MD, Division of Clinical Pharmacology, University of Massachusetts Medical Center, Worcester, MA 01655.
13/1/24083
above the seventy-fifth percentile for age and sex while adhering to the American Heart Association phase I diet. Other requirements included glycosylated hemoglobin levels (Hb AO within 50% above the upper limit of normal, plasma triglycerides below 350 mg /dl, and serum creatinine less than 1.5 mg/dl during screening. All patients gave written consent, and the protocol was approved by the Human Subjects Committee of the University of Massachusetts Medical Center (Worcester, Mass.). After screening, patients were instructed in the American Heart Association phase I lipid-lowering diet by a nutritionist; this diet was maintained for the entire study. Apart from the study drugs, no patient took any drug that would alter plasma lipids or interfere with glucose metabolism. Patients entered a single-blind study, beginning with a 6-week placebo baseline period. Seven patients continued to have adequate glucose control during the last week of the baseline period and entered a 7-week lovastatin treatment period. Three patients were men and four patients were women; all patients were white. Ages ranged from 48 to 61, with a mean of 57 years. All had fasting blood glucoses in the clinic and at home below 180 mg/ dl (mean, 145 mg/ O. Daily doses of chlorpropamide ranged from 125 to 750 mg, with a median of 500 mg daily. Metabolic studies were performed at the end of the placebo period, after the first 2 days of treatment with 20 mg lovastatin twice daily (with breakfast and dinner), and after 6 weeks of treatment. All patients had
467
CLIN PHARMACOL THER OCTOBER 1990
468 Johnson et al.
Baseline
250
Week
1
Week 6 200
-o 150
a)
0 0
CO
50
0
I
Fasting
1/2
2
1
4
3
Time (Hours) Fig. 1. Comparison of mean postprandial blood glucose levels before, 2 days after, and 6 weeks after starting treatment with 20 mg lovastatin administered twice daily.
the following evaluations done in a clinical research center. After fasting for at least 12 hours, blood was obtained for a full lipid analysis that included total cholesterol, triglycerides, lipoprotein cholesterol levels, and levels of apolipoprotein (apo) A-1 and B. Specimens were also obtained for plasma chlorpropamide and glucose. The usual morning dose of chlorpropamide was given, followed by a standardized breakfast consisting of 20% of the prescribed daily calories. Breakfast was consumed within a maximum of 15 minutes. Subsequent blood samples were obtained at 1/2, 1, 2, 3, and 4 hours after the breakfast for glucose levels. Aliquots of these specimens were frozen for later analysis for total 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase inhibitory activity, an estimate of lovastatin concentration. Samples were also obtained at 1, 2, 3, 4, 6, and 8 hours after breakfast for chlorpropamide concentration. Finally, specimens for serum chemistries and complete blood counts were obtained at the end of the seventh week of treatment.
Routine chemistries, complete blood counts, total cholesterol, triglycerides, high-density lipoprotein cholesterol (HDL-C), very low-density lipoprotein cholesterol (VLDL-C), and apo B were analyzed by use of the standard methods of SmithKline BioScience Laboratories, Van Nuys, Calif. Total cholesterol and triglycerides were measured enzymatically. HDL-C was measured enzymatically after phosphotungstic acid magnesium chloride extraction. VLDL-C was separated by ultracentrifugation and the cholesterol measured enzymatically. Low-density lipoprotein cholesterol (LDL-C) was calculated by the formula: LDL-C = TC
HDL-C
VLDL-C
in which TC is total cholesterol. Apo B was measured by antibody antigen complex laser nephlometry. Apo A-1, plasma glucose, and chlorpropamide were measured in the laboratory of Dr. Johnson (University of Massachusetts Medical Center, Worcester, Mass.). Apo A-1 was measured by a radioimmunodiffusion method
VOLUME 48 NUMBER 4
Lovastatin in diabetic patients 469
0-Baseline
200
Week
1
Week 6 180
E -6)
t-.5
_c
0
120
__-_r_
100
1
I
Fasting
//
I
1
I
2
I
3
I
I
4
1
6
I
I
8
Time (Hours) Fig. 2. Comparison of mean 8-hour plasma chlorpropamide levels before, 2 days after, and 6 weeks after starting treatment with 20 mg lovastatin administered twice daily.
by use of a kit (Tago, Inc., Burlingame, Calif.). Blood glucose was measured by use of a Beckman glucose analyzer (Beckman Instruments, Inc., Palo Alto, Calif.). Chlorpropamide was measured by use of lipid chromatography following solvent extraction after the method of Keal et al. ,3 substituting methyltert-butyl ether for ethyl ether as the extracting solvent. Chromatography was performed by use of the conditions suggested by Hill and Chrechiolo,4 with the substitution of 1-(1-methylpropy1)-3-(para-tolylsulfony1)urea (No. S40064-5, Alfred Bader Library, Milwaukee, Wis.) as the internal standard. A standard curve was generated from 50 to 500 lig / ml with use of spiked bovine serum albumin specimens processed with each batch of samples. Precision studies performed before the analysis of study samples demonstrated coefficients of variation of 1% at 50 p,g /m1 and 2.3% at 100 lig / ml. The limits of detection for the assay were determined to be 1.0 lig /ml. The assay for lovastatin was provided by Merck Sharp & Dohme Research Labo-
ratories (West Point, Pa.). Total HMG CoA reductase inhibitory activity, an estimate of lovastatin concentration, was measured by an automated modification of the method of Alberts et al.' after hydrolysis. Statistical analysis of the lipid parameters was done by use of the Wilcoxon signed-rank test for paired data. The area under the curve (AUC) values for glucose, chlorpropamide, and HMG CoA reductase inhibitory activity were also analyzed by use of the Wilcoxon signed-rank test. A multivariate analysis with Hotelling's one sample t test was done for glucose AUC for baseline and for day 2 and week 6 of lovastatin treatment. Significance was taken as p < 0.05. There was an 80% power to detect changes of 16% in total cholesterol, 18% in LDL cholesterol, and 36% in glucose AUC determinations.
RESULTS Administration of lovastatin for 6 weeks significantly reduced total cholesterol, LDL-C, and apo B compared
CLIN PHARMACOL THER OCTOBER 1990
470 Johnson et al.
Table I. Mean values and percentage changes in plasma lipids and lipoproteins after 6 weeks of lovastatin therapy LDL-C
TC
Number of Patients* Placebo (mg/dl)t Lovastatin (mg/ d1)1* Mean percent change (mg/d1)t
p Value
HDL-C
7
6
7
255.3 ± 20.0 192.7 ± 25.1 -24.0 ± 12.2
187.2 ± 18.7 133.3 ± 22.9 -28.4 ± 12.4
39.4 ± 7.4 40.1 -± 4.0
+3.6
0.05
0.05
_±
12.8
VLDL-C
6 27.5 ± 8.3 18.2 ± 6.5 -27.6 ± 37.1 NS
NS
TG 7
173.6 ± 57.4 134.3 ± 66.4
-22.5 ± 27.5 NS
TC, Total cholesterol; LDL-C, low-density lipoprotein cholesterol; HDL-C, high-density lipoprotein cholesterol; VLDL-C, very low-density lipoprotein cholesterol; TG, triglycerides; apo B, apolipoprotein B; apo A-1, apolipoprotein A-1; NS, not significant. *Measured VLDL and LDL not available for one patient; apo B not available for another. "'Data are mean values ± SD.
Table II. Plasma HMG CoA reductase inhibitory activity during lovastatin treatment Nondiabetic control subjects
Diabetic patients
C,ax
Parameter
Day 2
Week 6
(ng-eq/ml)
25.0 ± 7.2 68.8 ± 16.9
23.3 ± 9.9 55.5 ± 25.4
AUC (hr ng-eq/m1)
80 mg daily dose*
55.9 ± 42 135
±
101
20 mg
b.i.d.t 18.1
63.2
Data are mean values ± SD. Cm, Peak serum concentration; AUC, area under the plasma concentration-time curve. *Values during 9-day multiple dose regimen of 80 mg once daily. tPredicted values derived from a multiple dose study of 80 mg once daily in hypercholesterolemic nondiabetic subjects, assuming a linear relationship with dose for both Crna and AUC.
with baseline. The mean percent reductions were 24% for total cholesterol, 28% for LDL-C, and 24% for apo B. The reduction in VLDL-C (28%) and triglycerides (23%) and the increase in HDL-C (3.6%) did not reach statistical significance. There was no statistically significant change in apo A-1. The mean lipid values and percent changes are shown in Table I. In all but one patient, total cholesterol was below 200 mg/ dl after 6 weeks of therapy with 20 mg lovastatin twice daily. This patient was treated for an additional 4 weeks with 40 mg lovastatin twice daily. The respective lipid values in this patient at the end of the placebo period and after treatment with 20 mg and 40 mg lovastatin twice daily were as follows: total cholesterol, 262, 235, and 169 mg /dl; LDL-C, 205, 170, and 116 mg /d1; and apo B, 104, 94, and 70 mg /d1. Diabetic control was maintained during the study. Neither the mean fasting glucose level nor the mean 4hour glucose AUC was significantly changed from the placebo period to the lovastatin 2-day or 6-week treatment periods. The mean fasting glucose levels were 123.7 mg/di at baseline, 123.7 mg/di after 2 days of
lovastatin therapy, and 131.0 mg/di after 6 weeks of lovastatin therapy. The mean 4-hour AUC values were 772.9 mg hr/dl at baseline, 742.4 mg hr/ dl after 2 days of lovastatin therapy, and 727.1 mg hr/dl after 6 weeks of lovastatin therapy. There was a possible tendency toward lower glucose levels 2 and 3 hours postprandially. Mean glucose profiles are shown in Fig. 1. The mean plasma chlorpropamide 8 hour profiles, as shown in Fig. 2, were also unchanged during the study. The mean ( -± SD) AUC values of 1131.6 ( ±- 809.0) Fig hr/ ml after 2 days and 1136.9 ( -± 768.3) lig hr/ml after 6 weeks of lovastatin therapy were not significantly different from the value of 1135.4 ( -± 747.2) lig hr/ml at baseline. No patient required a change in chlorpropamide dose during lovastatin treatment. Plasma HMG CoA reductase inhibitory activity calculated as 4-hour AUC levels were compared with data obtained from a previous multiple dose pharmacokinetic study in nondiabetic hypercholesterolemic patients. The peak level (Cmax) and the AUC in the diabetic patients at 2 days and 6 weeks of lovastatin therapy, as shown
VOLUME 48 NUMBER 4
Lovastatin in diabetic patients
Apo B
Apo A-1
6 98.5 ± 7.9 74.0 ± 12.3 24.4 ± 13.8
148.8 ± 21.8 152.9 ± 25.9 +3.7 ± 19.5
0.05
NS
7
in Table II, were similar to those extrapolated to a 20
mg b.i.d. dose from a study of hypercholesterolemic nondiabetic patients treated for 9 days with 80 mg lovastatin once daily. There was no elevation in serum transaminase, alkaline phosphatase, or creatinine phosphokinase levels, and no patient experienced any drug-related adverse effects during this study.
DISCUSSION It is well established that the risk of developing cardiovascular disease is associated with elevated blood cholesterol levels.6-8 Lowering blood cholesterol level appears to reduce those risks9"0 by about 2% for each 1% that blood cholesterol is lowered. Further, there is some evidence that long-term control of hypercholesterolemia can reverse coronary atherosclerosis." Coronary heart disease is at least twice as common in diabetic patients as in the general population,' and is the principal cause of death among white diabetic patients.' This may be related to known abnormalities in lipoprotein metabolism, inasmuch as NIDDM is usually accompanied by abnormal metabolism of VLDL, LDL, and HDL. Common plasma lipid abnormalities include elevations of total and VLDL triglycerides, and of VLDL and LDL cholesterol, with decrease in HDL cholesterol."' Some of these abnormalities persist in patients with noninsulin dependent diabetes despite therapy, although this may be related to the frequent failure to achieve total control of hyperglycemia:6J' The capability to reduce plasma cholesterol substantially has improved after the recent introduction of lovastatin."' This drug is the most widely studied representative of those agents that inhibit the enzyme HMG-CoA reductase. By inhibiting this rate-limiting enzyme in the biosynthesis of cholesterol, lovastatin may reduce VLDL cholesterol production. It may also increase catabolism of LDL and VLDL cholesterol by increasing the activity of LDL receptors in the liver.
471
Two recent studies have demonstrated that lovastatin may be equally effective in improving plasma lipid abnormalities in NIDDM.22' Our findings support the conclusion that lovastatin is as effective in diabetic patients as it is in nondiabetic subjects. Because there is evidence of both increased production and clearance of LDL in NIDDM,' this suggests that the predominant effect of lovastatin is to depress production of VLDL in diabetic patients. Previous studies have suggested a low incidence of adverse effects of lovastatin, and there were no adverse effects of any kind noted in our small
group of subjects. Lovastatin is an inactive lactone that is concentrated in the liver after intestinal absorption. It is extensively metabolized in the liver, and its activity is dependent on metabolites, principally the 13-hydroxyl-acid form. Relatively low concentrations of the active metabolites circulate in blood, where they are extensively bound to plasma proteins. It might be anticipated that interaction could occur with other drugs that are protein bound or that are extensively metabolized in the liver. However, no evidence of any interaction with antipyrine has been found," suggesting that lovastatin would not be expected to interact with drugs that affect the cytochrome P-450 system. There is also no evidence from pharmacokinetic-pharmacodynamic interaction studies that lovastatin interacts with propranolol, digoxin, or warfarin. Chlorpropamide is both extensively protein bound and mainly eliminated by hepatic metabolism. However, we found no evidence to suggest any influence of concurrently administered lovastatin on the steady-state kinetics of chlorpropamide. Less than 1% of circulating chlorpropamide is bound to lipoproteins, so the therapeutic effect of lovastatin should not substantially affect chlorpropamide transport. It also appears unlikely that chlorpropamide interferes with plasma levels of lovastatin, measured as HMG-Co A reductase inhibitory activity. Levels in our patients were similar to dose-adjusted levels from nondiabetic subjects who were treated in multiple dose studies with 80 mg lovastatin daily. Gemfibrozil" and nicotinic acid" have been reported to impair control of hyperglycemia moderately in diabetic patients. Our study found no evidence of any such effect of lovastatin. An observed tendency for slight reduction in blood glucose 2 to 3 hours after breakfast was not considered to be of any clinical importance. Because the level of diabetic control was not changed, improvements in plasma lipids were entirely attributable to the effects of lovastatin therapy. Further studies
472 Johnson et al. of the effectiveness of lovastatin in NIDDM patients with hyperlipidemia are recommended in view of the possibility that the increased incidence of coronary heart disease in diabetic patients may be reduced by improving lipids. This study suggests that, in patients with NIDDM, control of glucose is not altered by lovastatin and that there is no need to change the dose of either lovastatin or chlorpropamide in these patients. References Kannel WB, McGee DL. Diabetes and cardiovascular disease: the Framingham study. JAMA 1979;241: 2035-8. Garg A, Grundy SM. Lovastatin for lowering cholesterol levels in non-insulin-dependent diabetes mellitus. N Engl J Med 1988;318:81-6. Keal J, Stockley C, Somogyi A. Simultaneous determination of tolbutamide and its hydroxy and carboxy metabolites in plasma and urine by high-performance liquid chromatography. J Chromatogr 1986;378:237-41. Hill RE, Crechiolo J. Determination of serum tolbutamide and chlorpropamide by high-performance liquid chromatography. J Chromatogr 1978;145:165-8. Alberts AW, Chen J, Kuron G, et al. Mevinolin: a highly potent competitive inhibitor of hydroxymethylglutarylcoenzyme A reductase and a cholesterol-lowering agent. Proc Natl Acad Sci USA 1980;77:3957-61. Kannel WB, Castelli W, Gordon T, et al. Serum cholesterol, lipoproteins, and risk of coronary heart disease: the Framingham study. Ann Intern Med 1977;74:1-12. Multiple Risk Factor Intervention Trial Research Group. Multiple Risk Factor Intervention Trial: risk factor changes and mortality results. JAMA 1982;248:1465-77. Rose G, Shipley M. Plasma cholesterol concentration and death from coronary heart disease: 10 year results of the Whitehall study. Br Med J 1986;293:306-7. Lipid Research Clinics Program. The Lipid Research Clinics Coronary Primary Prevention Trial. II. The relationship of reduction in incidence of coronary heart disease to cholesterol lowering. JAMA 1984;251:36574. Canner PL, Berge KG, Wenger NK, et al. Fifteen year mortality in coronary drug project patients: long-term benefits with niacin. J Am Coll Cardiol 1986;8:1245-55. Blankenhorn DH, Nessim SA, Johnson RL, et al. Beneficial effects of combined colestipol-niacin therapy on coronary atherosclerosis and coronary venous bypass grafts. JAMA 1987;257:3233-40. Ruderman NB, Haudenschild C. Diabetes as an atherogenic factor. Prog Cardiovasc Dis 1984;26:373-412.
CLIN PHAR/V1ACOL THER OCTOBER 1990
Barrett-Connor E, Grundy SM, Holdbrook MJ. Plasma lipids and diabetes mellitus in an adult community. Am J Epidemiol 1982;115:657-63. Laakso M, Voutilainen E, Sarlund H, Aro A, Pyorala K, Penttila I. Serum lipids and lipoproteins in middleaged non-insulin-dependent diabetes. Atherosclerosis 1985;56:271-81. Howard By. Lipoprotein metabolism in diabetes mellitus. J Lipid Res 1987;28:613-28. Howard BV, Xiaoren P, Harper I, Foley JE, Cheung MC, Taskinen MR. Effect of sulfonylurea therapy on plasma lipids and high-density lipoprotein composition in noninsulin-dependent diabetes mellitus. Am J Med 1985; 79:78-85. Hollenbeck CB, Chen YDI, Greenfield MS, Lardinois CK, Reaven GM. Reduced plasma high density lipoprotein-cholesterol concentrations need not increase when hyperglycemia is controlled with insulin in noninsulin-dependent diabetes mellitus. J Clin Endocrinol Metab 1985;62:605-8. Tobert JA, Hitzenberger G, Kukovetz WR, et al. Rapid and substantial lowering of human serum cholesterol by mevinolin (MK-803), an inhibitor of hydroxymethylglutaryl-coenzyme A reductase. Atherosclerosis 1982;41:61-5. Illingworth DR, Sextron GJ. Hypocholesterolemic effects of mevinolin in patients with heterozygous familiar hypercholesterolemia. J Clin Invest 1984;74:1972-8. Havel RJ, Hunninghake DB, Illingworth DR, et al. A multicenter study of lovastatin (mevinolin) in the therapy of heterozygous familial hypercholesterolemia. Ann Intern Med 1987;107:609-15. Yoshino G, Kazumi T, Kasama T, et al. Effects of CS514, an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, on lipoprotein and apolipoprotein in plasma of hypercholesterolemic diabetes. Diabetes Res Clin Pract 1986;2:179-81. Kissebah AH, Alfarsi S, Evans DJ, Adams PW. Plasma low density lipoprotein transport kinetics in non-insulindependent diabetes mellitus. J Clin Invest 1983;71:65567. Hunninghake DB, Hibbard DM. Effect of lovastatin and simvastatin on hepatic oxidative drug metabolizing enzymes [Abstract]. Presented at the Eighth International Symposium on Atherosclerosis, Rome, Italy, 1988:390. Marks J, Howard AN. A comparative study of gemfibrozil and clofibrate in the treatment of hyperlipidemia in patients with maturity-onset diabetes. Res Clin Forums 1982;4:95-103. Gurian H, Aldersberg D. The effect of large doses of nicotinic acid on circulating lipids and carbohydrate tolerance. Am J Med Sci 1959;237:12-22.
treated with chlorpropamide Patients with noninsulin dependent diabetes mellitus (NIDDM) have a higher risk of atherosclerotic cardiovascular disease than nondiabetic subjects. In seven patients with both hypercholesterolemia and NIDDM controlled by chlorpropamide, lovastatin (20 mg b.i.d. for 6 weeks) lowered low-density lipoprotein cholesterol by 28%, total cholesterol by 24%, and apolipoprotein B by 24%. Lovastatin levels for a 4-hour period (measured as 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitory activity) were similar to those measured previously in nondiabetic patients. Lovastatin did not alter chlorpropamide kinetics or glycemic profiles. No patient had an elevation in serum transaminases or creatinine phosphokinase, and no patient had any other laboratory or clinical drug-related adverse experience during the study. Lovastatin was as effective in reducing low-density lipoprotein cholesterol in patients with NIDDM as in nondiabetic subjects. Diabetic control was unaltered, and no evidence of alteration in lovastatin or chlorpropamide blood levels was noted. (CLIN PHARMACOL THER 1990;48:467-72.)
Brian F. Johnson, MD, Patrice LaBelle, MD, John Wilson, PhD, Judy Allan, BS, Robert V. Zupkis, PhD, and Philip D. Ronca, BS Worcester, Mass., and West Point, Pa. Patients with noninsulin dependent diabetes mellitus (NIDDM) have a higher risk of atherosclerotic cardiovascular disease than that of nondiabetic patients.' It is probable that the lipid abnormalities found in these patients play a role in the development of their atherosclerosis. It has been shown that lovastatin can improve some of the lipid abnormalities in diabetic patients' to an extent similar to those in nondiabetic subjects with lipid abnormalities. The purpose of our study was to confirm the effects of lovastatin in hypercholesterolemic patients with NIDDM and to determine whether the drug has any important effect on control of diabetes. A related objective was to determine whether there was any interaction between lovastatin and chlorpropamide, an oral agent commonly used to treat this type of diabetic patient.
METHODS The main criteria for selection of patients for the study were the presence of NIDDM under reasonable control with stable doses of chlorpropamide and persistent elevation of plasma total cholesterol to levels From the Division of Clinical Pharmacology, University of Massachusetts Medical Center, Worcester, and Merck Sharp & Dohme Research Laboratories, West Point. Received for publication March 30, 1990; accepted July 26, 1990. Reprint requests: Brian F. Johnson, MD, Division of Clinical Pharmacology, University of Massachusetts Medical Center, Worcester, MA 01655.
13/1/24083
above the seventy-fifth percentile for age and sex while adhering to the American Heart Association phase I diet. Other requirements included glycosylated hemoglobin levels (Hb AO within 50% above the upper limit of normal, plasma triglycerides below 350 mg /dl, and serum creatinine less than 1.5 mg/dl during screening. All patients gave written consent, and the protocol was approved by the Human Subjects Committee of the University of Massachusetts Medical Center (Worcester, Mass.). After screening, patients were instructed in the American Heart Association phase I lipid-lowering diet by a nutritionist; this diet was maintained for the entire study. Apart from the study drugs, no patient took any drug that would alter plasma lipids or interfere with glucose metabolism. Patients entered a single-blind study, beginning with a 6-week placebo baseline period. Seven patients continued to have adequate glucose control during the last week of the baseline period and entered a 7-week lovastatin treatment period. Three patients were men and four patients were women; all patients were white. Ages ranged from 48 to 61, with a mean of 57 years. All had fasting blood glucoses in the clinic and at home below 180 mg/ dl (mean, 145 mg/ O. Daily doses of chlorpropamide ranged from 125 to 750 mg, with a median of 500 mg daily. Metabolic studies were performed at the end of the placebo period, after the first 2 days of treatment with 20 mg lovastatin twice daily (with breakfast and dinner), and after 6 weeks of treatment. All patients had
467
CLIN PHARMACOL THER OCTOBER 1990
468 Johnson et al.
Baseline
250
Week
1
Week 6 200
-o 150
a)
0 0
CO
50
0
I
Fasting
1/2
2
1
4
3
Time (Hours) Fig. 1. Comparison of mean postprandial blood glucose levels before, 2 days after, and 6 weeks after starting treatment with 20 mg lovastatin administered twice daily.
the following evaluations done in a clinical research center. After fasting for at least 12 hours, blood was obtained for a full lipid analysis that included total cholesterol, triglycerides, lipoprotein cholesterol levels, and levels of apolipoprotein (apo) A-1 and B. Specimens were also obtained for plasma chlorpropamide and glucose. The usual morning dose of chlorpropamide was given, followed by a standardized breakfast consisting of 20% of the prescribed daily calories. Breakfast was consumed within a maximum of 15 minutes. Subsequent blood samples were obtained at 1/2, 1, 2, 3, and 4 hours after the breakfast for glucose levels. Aliquots of these specimens were frozen for later analysis for total 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase inhibitory activity, an estimate of lovastatin concentration. Samples were also obtained at 1, 2, 3, 4, 6, and 8 hours after breakfast for chlorpropamide concentration. Finally, specimens for serum chemistries and complete blood counts were obtained at the end of the seventh week of treatment.
Routine chemistries, complete blood counts, total cholesterol, triglycerides, high-density lipoprotein cholesterol (HDL-C), very low-density lipoprotein cholesterol (VLDL-C), and apo B were analyzed by use of the standard methods of SmithKline BioScience Laboratories, Van Nuys, Calif. Total cholesterol and triglycerides were measured enzymatically. HDL-C was measured enzymatically after phosphotungstic acid magnesium chloride extraction. VLDL-C was separated by ultracentrifugation and the cholesterol measured enzymatically. Low-density lipoprotein cholesterol (LDL-C) was calculated by the formula: LDL-C = TC
HDL-C
VLDL-C
in which TC is total cholesterol. Apo B was measured by antibody antigen complex laser nephlometry. Apo A-1, plasma glucose, and chlorpropamide were measured in the laboratory of Dr. Johnson (University of Massachusetts Medical Center, Worcester, Mass.). Apo A-1 was measured by a radioimmunodiffusion method
VOLUME 48 NUMBER 4
Lovastatin in diabetic patients 469
0-Baseline
200
Week
1
Week 6 180
E -6)
t-.5
_c
0
120
__-_r_
100
1
I
Fasting
//
I
1
I
2
I
3
I
I
4
1
6
I
I
8
Time (Hours) Fig. 2. Comparison of mean 8-hour plasma chlorpropamide levels before, 2 days after, and 6 weeks after starting treatment with 20 mg lovastatin administered twice daily.
by use of a kit (Tago, Inc., Burlingame, Calif.). Blood glucose was measured by use of a Beckman glucose analyzer (Beckman Instruments, Inc., Palo Alto, Calif.). Chlorpropamide was measured by use of lipid chromatography following solvent extraction after the method of Keal et al. ,3 substituting methyltert-butyl ether for ethyl ether as the extracting solvent. Chromatography was performed by use of the conditions suggested by Hill and Chrechiolo,4 with the substitution of 1-(1-methylpropy1)-3-(para-tolylsulfony1)urea (No. S40064-5, Alfred Bader Library, Milwaukee, Wis.) as the internal standard. A standard curve was generated from 50 to 500 lig / ml with use of spiked bovine serum albumin specimens processed with each batch of samples. Precision studies performed before the analysis of study samples demonstrated coefficients of variation of 1% at 50 p,g /m1 and 2.3% at 100 lig / ml. The limits of detection for the assay were determined to be 1.0 lig /ml. The assay for lovastatin was provided by Merck Sharp & Dohme Research Labo-
ratories (West Point, Pa.). Total HMG CoA reductase inhibitory activity, an estimate of lovastatin concentration, was measured by an automated modification of the method of Alberts et al.' after hydrolysis. Statistical analysis of the lipid parameters was done by use of the Wilcoxon signed-rank test for paired data. The area under the curve (AUC) values for glucose, chlorpropamide, and HMG CoA reductase inhibitory activity were also analyzed by use of the Wilcoxon signed-rank test. A multivariate analysis with Hotelling's one sample t test was done for glucose AUC for baseline and for day 2 and week 6 of lovastatin treatment. Significance was taken as p < 0.05. There was an 80% power to detect changes of 16% in total cholesterol, 18% in LDL cholesterol, and 36% in glucose AUC determinations.
RESULTS Administration of lovastatin for 6 weeks significantly reduced total cholesterol, LDL-C, and apo B compared
CLIN PHARMACOL THER OCTOBER 1990
470 Johnson et al.
Table I. Mean values and percentage changes in plasma lipids and lipoproteins after 6 weeks of lovastatin therapy LDL-C
TC
Number of Patients* Placebo (mg/dl)t Lovastatin (mg/ d1)1* Mean percent change (mg/d1)t
p Value
HDL-C
7
6
7
255.3 ± 20.0 192.7 ± 25.1 -24.0 ± 12.2
187.2 ± 18.7 133.3 ± 22.9 -28.4 ± 12.4
39.4 ± 7.4 40.1 -± 4.0
+3.6
0.05
0.05
_±
12.8
VLDL-C
6 27.5 ± 8.3 18.2 ± 6.5 -27.6 ± 37.1 NS
NS
TG 7
173.6 ± 57.4 134.3 ± 66.4
-22.5 ± 27.5 NS
TC, Total cholesterol; LDL-C, low-density lipoprotein cholesterol; HDL-C, high-density lipoprotein cholesterol; VLDL-C, very low-density lipoprotein cholesterol; TG, triglycerides; apo B, apolipoprotein B; apo A-1, apolipoprotein A-1; NS, not significant. *Measured VLDL and LDL not available for one patient; apo B not available for another. "'Data are mean values ± SD.
Table II. Plasma HMG CoA reductase inhibitory activity during lovastatin treatment Nondiabetic control subjects
Diabetic patients
C,ax
Parameter
Day 2
Week 6
(ng-eq/ml)
25.0 ± 7.2 68.8 ± 16.9
23.3 ± 9.9 55.5 ± 25.4
AUC (hr ng-eq/m1)
80 mg daily dose*
55.9 ± 42 135
±
101
20 mg
b.i.d.t 18.1
63.2
Data are mean values ± SD. Cm, Peak serum concentration; AUC, area under the plasma concentration-time curve. *Values during 9-day multiple dose regimen of 80 mg once daily. tPredicted values derived from a multiple dose study of 80 mg once daily in hypercholesterolemic nondiabetic subjects, assuming a linear relationship with dose for both Crna and AUC.
with baseline. The mean percent reductions were 24% for total cholesterol, 28% for LDL-C, and 24% for apo B. The reduction in VLDL-C (28%) and triglycerides (23%) and the increase in HDL-C (3.6%) did not reach statistical significance. There was no statistically significant change in apo A-1. The mean lipid values and percent changes are shown in Table I. In all but one patient, total cholesterol was below 200 mg/ dl after 6 weeks of therapy with 20 mg lovastatin twice daily. This patient was treated for an additional 4 weeks with 40 mg lovastatin twice daily. The respective lipid values in this patient at the end of the placebo period and after treatment with 20 mg and 40 mg lovastatin twice daily were as follows: total cholesterol, 262, 235, and 169 mg /dl; LDL-C, 205, 170, and 116 mg /d1; and apo B, 104, 94, and 70 mg /d1. Diabetic control was maintained during the study. Neither the mean fasting glucose level nor the mean 4hour glucose AUC was significantly changed from the placebo period to the lovastatin 2-day or 6-week treatment periods. The mean fasting glucose levels were 123.7 mg/di at baseline, 123.7 mg/di after 2 days of
lovastatin therapy, and 131.0 mg/di after 6 weeks of lovastatin therapy. The mean 4-hour AUC values were 772.9 mg hr/dl at baseline, 742.4 mg hr/ dl after 2 days of lovastatin therapy, and 727.1 mg hr/dl after 6 weeks of lovastatin therapy. There was a possible tendency toward lower glucose levels 2 and 3 hours postprandially. Mean glucose profiles are shown in Fig. 1. The mean plasma chlorpropamide 8 hour profiles, as shown in Fig. 2, were also unchanged during the study. The mean ( -± SD) AUC values of 1131.6 ( ±- 809.0) Fig hr/ ml after 2 days and 1136.9 ( -± 768.3) lig hr/ml after 6 weeks of lovastatin therapy were not significantly different from the value of 1135.4 ( -± 747.2) lig hr/ml at baseline. No patient required a change in chlorpropamide dose during lovastatin treatment. Plasma HMG CoA reductase inhibitory activity calculated as 4-hour AUC levels were compared with data obtained from a previous multiple dose pharmacokinetic study in nondiabetic hypercholesterolemic patients. The peak level (Cmax) and the AUC in the diabetic patients at 2 days and 6 weeks of lovastatin therapy, as shown
VOLUME 48 NUMBER 4
Lovastatin in diabetic patients
Apo B
Apo A-1
6 98.5 ± 7.9 74.0 ± 12.3 24.4 ± 13.8
148.8 ± 21.8 152.9 ± 25.9 +3.7 ± 19.5
0.05
NS
7
in Table II, were similar to those extrapolated to a 20
mg b.i.d. dose from a study of hypercholesterolemic nondiabetic patients treated for 9 days with 80 mg lovastatin once daily. There was no elevation in serum transaminase, alkaline phosphatase, or creatinine phosphokinase levels, and no patient experienced any drug-related adverse effects during this study.
DISCUSSION It is well established that the risk of developing cardiovascular disease is associated with elevated blood cholesterol levels.6-8 Lowering blood cholesterol level appears to reduce those risks9"0 by about 2% for each 1% that blood cholesterol is lowered. Further, there is some evidence that long-term control of hypercholesterolemia can reverse coronary atherosclerosis." Coronary heart disease is at least twice as common in diabetic patients as in the general population,' and is the principal cause of death among white diabetic patients.' This may be related to known abnormalities in lipoprotein metabolism, inasmuch as NIDDM is usually accompanied by abnormal metabolism of VLDL, LDL, and HDL. Common plasma lipid abnormalities include elevations of total and VLDL triglycerides, and of VLDL and LDL cholesterol, with decrease in HDL cholesterol."' Some of these abnormalities persist in patients with noninsulin dependent diabetes despite therapy, although this may be related to the frequent failure to achieve total control of hyperglycemia:6J' The capability to reduce plasma cholesterol substantially has improved after the recent introduction of lovastatin."' This drug is the most widely studied representative of those agents that inhibit the enzyme HMG-CoA reductase. By inhibiting this rate-limiting enzyme in the biosynthesis of cholesterol, lovastatin may reduce VLDL cholesterol production. It may also increase catabolism of LDL and VLDL cholesterol by increasing the activity of LDL receptors in the liver.
471
Two recent studies have demonstrated that lovastatin may be equally effective in improving plasma lipid abnormalities in NIDDM.22' Our findings support the conclusion that lovastatin is as effective in diabetic patients as it is in nondiabetic subjects. Because there is evidence of both increased production and clearance of LDL in NIDDM,' this suggests that the predominant effect of lovastatin is to depress production of VLDL in diabetic patients. Previous studies have suggested a low incidence of adverse effects of lovastatin, and there were no adverse effects of any kind noted in our small
group of subjects. Lovastatin is an inactive lactone that is concentrated in the liver after intestinal absorption. It is extensively metabolized in the liver, and its activity is dependent on metabolites, principally the 13-hydroxyl-acid form. Relatively low concentrations of the active metabolites circulate in blood, where they are extensively bound to plasma proteins. It might be anticipated that interaction could occur with other drugs that are protein bound or that are extensively metabolized in the liver. However, no evidence of any interaction with antipyrine has been found," suggesting that lovastatin would not be expected to interact with drugs that affect the cytochrome P-450 system. There is also no evidence from pharmacokinetic-pharmacodynamic interaction studies that lovastatin interacts with propranolol, digoxin, or warfarin. Chlorpropamide is both extensively protein bound and mainly eliminated by hepatic metabolism. However, we found no evidence to suggest any influence of concurrently administered lovastatin on the steady-state kinetics of chlorpropamide. Less than 1% of circulating chlorpropamide is bound to lipoproteins, so the therapeutic effect of lovastatin should not substantially affect chlorpropamide transport. It also appears unlikely that chlorpropamide interferes with plasma levels of lovastatin, measured as HMG-Co A reductase inhibitory activity. Levels in our patients were similar to dose-adjusted levels from nondiabetic subjects who were treated in multiple dose studies with 80 mg lovastatin daily. Gemfibrozil" and nicotinic acid" have been reported to impair control of hyperglycemia moderately in diabetic patients. Our study found no evidence of any such effect of lovastatin. An observed tendency for slight reduction in blood glucose 2 to 3 hours after breakfast was not considered to be of any clinical importance. Because the level of diabetic control was not changed, improvements in plasma lipids were entirely attributable to the effects of lovastatin therapy. Further studies
472 Johnson et al. of the effectiveness of lovastatin in NIDDM patients with hyperlipidemia are recommended in view of the possibility that the increased incidence of coronary heart disease in diabetic patients may be reduced by improving lipids. This study suggests that, in patients with NIDDM, control of glucose is not altered by lovastatin and that there is no need to change the dose of either lovastatin or chlorpropamide in these patients. References Kannel WB, McGee DL. Diabetes and cardiovascular disease: the Framingham study. JAMA 1979;241: 2035-8. Garg A, Grundy SM. Lovastatin for lowering cholesterol levels in non-insulin-dependent diabetes mellitus. N Engl J Med 1988;318:81-6. Keal J, Stockley C, Somogyi A. Simultaneous determination of tolbutamide and its hydroxy and carboxy metabolites in plasma and urine by high-performance liquid chromatography. J Chromatogr 1986;378:237-41. Hill RE, Crechiolo J. Determination of serum tolbutamide and chlorpropamide by high-performance liquid chromatography. J Chromatogr 1978;145:165-8. Alberts AW, Chen J, Kuron G, et al. Mevinolin: a highly potent competitive inhibitor of hydroxymethylglutarylcoenzyme A reductase and a cholesterol-lowering agent. Proc Natl Acad Sci USA 1980;77:3957-61. Kannel WB, Castelli W, Gordon T, et al. Serum cholesterol, lipoproteins, and risk of coronary heart disease: the Framingham study. Ann Intern Med 1977;74:1-12. Multiple Risk Factor Intervention Trial Research Group. Multiple Risk Factor Intervention Trial: risk factor changes and mortality results. JAMA 1982;248:1465-77. Rose G, Shipley M. Plasma cholesterol concentration and death from coronary heart disease: 10 year results of the Whitehall study. Br Med J 1986;293:306-7. Lipid Research Clinics Program. The Lipid Research Clinics Coronary Primary Prevention Trial. II. The relationship of reduction in incidence of coronary heart disease to cholesterol lowering. JAMA 1984;251:36574. Canner PL, Berge KG, Wenger NK, et al. Fifteen year mortality in coronary drug project patients: long-term benefits with niacin. J Am Coll Cardiol 1986;8:1245-55. Blankenhorn DH, Nessim SA, Johnson RL, et al. Beneficial effects of combined colestipol-niacin therapy on coronary atherosclerosis and coronary venous bypass grafts. JAMA 1987;257:3233-40. Ruderman NB, Haudenschild C. Diabetes as an atherogenic factor. Prog Cardiovasc Dis 1984;26:373-412.
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Barrett-Connor E, Grundy SM, Holdbrook MJ. Plasma lipids and diabetes mellitus in an adult community. Am J Epidemiol 1982;115:657-63. Laakso M, Voutilainen E, Sarlund H, Aro A, Pyorala K, Penttila I. Serum lipids and lipoproteins in middleaged non-insulin-dependent diabetes. Atherosclerosis 1985;56:271-81. Howard By. Lipoprotein metabolism in diabetes mellitus. J Lipid Res 1987;28:613-28. Howard BV, Xiaoren P, Harper I, Foley JE, Cheung MC, Taskinen MR. Effect of sulfonylurea therapy on plasma lipids and high-density lipoprotein composition in noninsulin-dependent diabetes mellitus. Am J Med 1985; 79:78-85. Hollenbeck CB, Chen YDI, Greenfield MS, Lardinois CK, Reaven GM. Reduced plasma high density lipoprotein-cholesterol concentrations need not increase when hyperglycemia is controlled with insulin in noninsulin-dependent diabetes mellitus. J Clin Endocrinol Metab 1985;62:605-8. Tobert JA, Hitzenberger G, Kukovetz WR, et al. Rapid and substantial lowering of human serum cholesterol by mevinolin (MK-803), an inhibitor of hydroxymethylglutaryl-coenzyme A reductase. Atherosclerosis 1982;41:61-5. Illingworth DR, Sextron GJ. Hypocholesterolemic effects of mevinolin in patients with heterozygous familiar hypercholesterolemia. J Clin Invest 1984;74:1972-8. Havel RJ, Hunninghake DB, Illingworth DR, et al. A multicenter study of lovastatin (mevinolin) in the therapy of heterozygous familial hypercholesterolemia. Ann Intern Med 1987;107:609-15. Yoshino G, Kazumi T, Kasama T, et al. Effects of CS514, an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, on lipoprotein and apolipoprotein in plasma of hypercholesterolemic diabetes. Diabetes Res Clin Pract 1986;2:179-81. Kissebah AH, Alfarsi S, Evans DJ, Adams PW. Plasma low density lipoprotein transport kinetics in non-insulindependent diabetes mellitus. J Clin Invest 1983;71:65567. Hunninghake DB, Hibbard DM. Effect of lovastatin and simvastatin on hepatic oxidative drug metabolizing enzymes [Abstract]. Presented at the Eighth International Symposium on Atherosclerosis, Rome, Italy, 1988:390. Marks J, Howard AN. A comparative study of gemfibrozil and clofibrate in the treatment of hyperlipidemia in patients with maturity-onset diabetes. Res Clin Forums 1982;4:95-103. Gurian H, Aldersberg D. The effect of large doses of nicotinic acid on circulating lipids and carbohydrate tolerance. Am J Med Sci 1959;237:12-22.
