EurJ Clin Pharmacol (1992) 43:93-95
© Springer-Verlag 1992
The pharmacokinetics of tiopronin and its principal metabolite (2-mercaptopropionic acid) after oral administration to healthy volunteers B. Hercelin 1, E Leroy 2, A. Nicolas 2, C. Gavriloff2, D. Chassard 3, J.-J.Th~bault 3, M.T. Reveillaud 4, M.-E Salles 4, and ENetter 5 Unit4 de Pharmacocinrtique-Biopharmacie, Laboratoires Cassenne, 95520 Osny, 2Laboratoire de Chimie Analytique, Centre National de la Recherche Scientifique, Unit6 de Recherche Associde 597, Facult6 de Pharmacie, B. P. 403, 54001 Nancy Cedex, 3Aster, H6pital Cognacq-Jay, 15 rue E. Millon, 75015 Paris, 4Laboratoires Cassenne, Tour Roussel-Hoechst, 92080 Paris La Drtense, and 5Laboratoire de Pharmacotogie, Centre National de la Recherche Scientifique, Unit6 de Recherche Associre 1288, Facult6 de M6decine, 54505 Vandoeuvre-Les-Nancy Cedex, France Received: July 1, 1991/Accepted in revised form: January 15,1992
Summary. We have studied the pharmacokinetics of tiopronin and its principal metabolite, 2-mercaptopropionic acid (2-MPA) in healthy volunteers after the oral administration of 500 mg (2 Acadione ® tablets), followed by simultaneous assay of the two compounds in plasma over a period of 48 h using a new method (emission of fluorescence after H P L C and post-column derivatization by pyrene-maleimide). The absorption of tiopronin was slow (tmax between 4 and 6 h) and the plasma concentrations subsequently fell biexponentially. The principal metabolite 2-MPA appeared later in the plasma (tmaxbetween 10 and 12 h after a tag-time of 3 h) then disappeared monoexponentially. About 15 % of the tiopronin was metabolized to 2-MPA.
12, 24, and 48 h after administration. The plasma was separated immediately and frozen at - 70 °C within 20 rain. After thawing of the plasma samples, precipitation of proteins, and reduction by tributylphosphine, tiopronin and 2-MPA were assayed by liquid chromatography. Separation was achieved on a reversed-phase column by ionpairing with cetrimonium bromide. Post-column derivatization with a selective thioI reagent, pyrenemaleimide, was performed and the corresponding derivatives were monitored by fluorometry [9]. The method included an initial reduction of the disulphide bonds; the plasma concentrations obtained therefore rigorously corresponded to (a) all of the circulating molecules reducible to tiopronin and (b) all of the circulating molecules reducible to 2-MPA. The limits of detection of the assay were 0.1 gg-ml-1 for tiopronin and 0.02 gg.ml ! for 2-mercaptopropionic acid. The pharmacokinetics were calculated by means of standard methods (linear trapezoidal method, linear regression of the termi-
Key words: Tiopronin, 2-mercaptopropionic acid; pharmacokinetics, healthy volunteers CH3-CH-CO-NH-CH2-COOH
]
i
Tiopronin, or 2-mercaptopropionylglycine (2-MPG), is a thiol derivative which has been used for several years in patients with cystine stones and also more recently in the long-term treatment of rheumatoid arthritis [1-8]. Tiopronin is structurally similar to D-penicillamine (Fig. 1). Data on the in vivo fate of tiopronin are recent and limited, because of analytical difficulties. Our objective was therefore to evaluate the pharmacokinetics of tiopronin and its prinicpal metabolite, 2-mercaptopropionic acid, in healthy volunteers, using a specific and sensitive assay for the two compounds.
SH 2-mercaptopropionylglycine, 2-MPG, tiopronin j \
/
Moderate oxidation
/
i Disulphide bonds - symmetrical asymmetrical
\
i
Strong oxidation
Hydrolysis
\
Sulphoxide Sulphone etc.
(2S-HpA)
]
/\ Methods After approval from the Ethics Committee of H6pital Cognacq-Jay in Paris, t2 consenting male Caucasian volunteers, mean age 23 (19 to 31) y and mean weight 73 (58 to 89) kg took a single oral dose of 500 mg of tiopronin as two tablets of Acadione®(Laboratoires Cassenne, France), containing 250 mg of the active substance, with 100 ml of water. Blood samples from each subject were collected in EDTAcoated vials just before administration and at 1, 2, 3, 4, 4.5, 5, 6, 8, 10,
Moderate oxidation
Strong oxidation
IDisulphide bonds
Sulphoxide1 Sulphone ]
/
\
Fig. 1. The chemical structure of tiopronin and the possible routes of its metabolism
94 10~0 ~Z~ZZ~ZZ:Z?2ZZZZZ~Zi~ZZZZZZ~ZZZZ-ZZZ~Z~2~ZZZZ~Z2~Z~ZZ~Z~Z~ZZ~ZZ~Z~ZZZZ2~
i...................
170 i:Z::
~. . . . . . . . . . . . . . . . . . . . . . . . . . . .
. ...........................
i ................................
~. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
i
beyond) Z:=;ZZZZTZZE:2::EZZZZZZZ2ZZZZZZ~ZZZZZ,ZZZZZZZZ::2iZZZZZZZZEZZZZZ i
:.......................
i................................!..................................i.............................i
8
N
0,01
0
10
20
30
40
50
Time ( h )
Fig.2. Mean plasma concentrations of tiopronin ( • ) and 2-MPA (O) after oral administration of 500 mg of tiopronin to 12 healthy volunteers
nal part of the log concentration versus time curve, etc) using a specificprogram created with Lotus 1-2-3;mean values, standard deviations (n-l), and coefficients of variation were calculated for each measurement. Results The time-courses of the mean concentrations of tiopronin and 2-MPA are illustrated in Fig. 2. The pharmacokinetic results are presented in Table 1. Discussion
Plasma concentration measurements The determination of tiopronin in biological media presents certain difficulties for various reasons. First, as for Dpenicillamine, the assay of well-defined chemical entities is altered by the presence of endogenous molecules with similar analytical behaviour and by the probable existence of steady states between unconjugated tiopronin and various possible conjugated forms; second, the molecule is exTable 1, The pharmacokinetics of tiopronin and 2-MPA after oral administration of 500 mg to healthy volunteers Tiopronin
2-MPA
mean (SD) (n) mean (SD) (n)
lag time t~ Cmax tle2.x, ha~ AUC AUCo~/AUC MRT
posed in vivo to metabolism via several pathways, some of which are more or less reversible (e.g. oxidation with formation of disulphide bonds), while others are irreversible (e. g. hydrolysis of the amide group with the formation of 2-mercaptopropionic acid, oxidation to sulphoxide and
(h) (h) (gg. ml-') (h) (h) (gg.ml-I h) (%) (h)
(0.3) (0.7) 3.6 (0.8) 2.4 (0.8) 18.7 (10.3) 29.0 (10.7) 90.5 (9.3) 11.2 (2.0) 0.6
5.0
(12) 2.7 (12) 10.8 (12) 0.22 (Ii) (10) 7.6 (II) 3.5 (11) 97.1 (12) 18.4
(1.9) (12) (1.3) (12) (0.09)(12) (4.2) (10) (1.2) (i0) (5.9) (10) (3.6) (12)
[11,121
(Fig. 1).
Tiopronin was first assayed in plasma by direct polarography of dilute plasma in 1976 [13]; this technique lacked specificity, being unable to distinguish tiopronin from other circulating thiols. A new assay, using liquid chromatography and detection by UV absorption of the derivative obtained by reaction with furoyl chloride, was described in 1982 [14]. This method was suitable for assay" in aqueous solutions or urine, but its sensitivity was too low to measure plasma concentrations after the administration of a therapeutic dose of tiopronin. More recently, a specific and more sensitive method has been described using liquid chromatography of tiopronin followed by fluorescence detection after precolumn derivatization by N-(7-dimethylamino-4-methyl3-coumarinyl)-maleimide (DACM) [15]. The technique used in this study was based on the same principle, but used post-column pyrene-maleimide derivatization. The specificity was sufficient for the two wincipal chemical entities present, tiopronin and 2-MPA, to be analysed simultaneously. The limits of detection also allowed precise and complete description of the pharmacokinetics of the two substances.
The pharmacokinetics of tiopronin after oral administration After a lag time of about 0.5 h, tiopronin appeared in the circulation with a Cmaxof 3-4 gg' ml ~ at a tmax of 4-6 h. These results show that the absorption of the tiopronin from the gastrointestinal tract is slow; they are also in agreement with the results reported by Kagedal et at. [15] in 5 subjects. The plasma concentrations then fell biexponentially with half-lives of about 2.4 and 15-30 h. In other subjects, using a slightly different assay method, Carlsson et al. obtained similar values after the intravenous administration of 250 mg of tiopronin and mathematical smoothing of the curves, with half-lives of about 2 and 55 h [16]. The mean residence time of tiopronin was around 11 h.
Pharmacokinetics of the principal metabolite 2-MPA 2-mercaptopropionic acid appeared in the circulation with a tmaxof 10-12 h after a lag time of about 3 h. The subsequent elimination was monoexponential with a half-life of 4-12 h. The mean residence time of the metabolite was slightly longer (15 to 22 h) than that of tiopronin. The values of A U C for tiopronin and 2-MPA showed that 10-15 per cent of tiopronin was metabolized to 2-MPA. The low plasma concentrations of tiopronin during the terminal phase, the small fraction of the total A U C to which it contributes, and the mean residence time (about
95 11 h) suggest that the risk of a c c u m u l a t i o n during rep e a t e d dosing is m o d e r a t e and that twice daily administration is justified. T h e r e is no risk of a c c u m u l a t i o n of 2 - M P A in the b o d y during long-term treatment.
Acknowledgements. The authors are very grateful to Mrs G Veniger and Mrs MThenier for their invaluable assistance in the preparation of this paper.
References 1. Crossley M J, Spowage M, Hunneyball IM (1987) Studies on the effects of pharmacological agents on the antigen-induced arthrifts in balb/c mice. Drug Exp Clin Res 13:273--277 2. Amor B, Mdry C, De Gery A, Zizi M (1986) Tiopronin and rheumatoid polyarthritis. Rev Rhum Mal Osteoartic 53:39-43 3. Amor B, M6ry C, De Gery A (1988) Acadione, a new long-term treatment of rheumatoid polyarthritis. Rev Rhum Mal Osteoartic 55:462--466 4. Sigaud M, Mangars Y, Maisonneuve H, Prost A (1988) Tiopronin in 69 cases of rheumatoid polyarthritis pretreated by D-penicillamine. Rev Rhum Mal Osteoartic 55:467-471 5. Mordini M, Guidoni G, Maestrini M, Buonavia A, Lavagni A (1989) Basic treatment of rheumatoid arthritis with tiopronin: a study of 25 cases. Minerva Med 80:1019-1023 6. Delecoeuillerie G (1989) Tolerance and efficacy of tiopronin, a new long-term treatment of rheumatoid polyarthritis. Rev Rhum Mal Osteoartic 56:38-42 7. Ferraccioli GF, Salaffi F, Nervetti A, Manganelli P (1989) Longterm outcome with gold thiosulfate and tiopronin in 200 rheumatoid patients. Clin Exp Rheumatol 7:577-581 8. Sany J, Combe B, Verdie-Petibon D, Tagemouati A, Daures JP (1990) Study of the tolerance of ftopronin (Acadione) in long-
term treatment of rheumatoid polyarthritis. Rev Rhum Mal Osteoartic 57:105-111 9. Leroy R Nicolas A, Gavriloff C, Matt M, Netter R Bannwarth B, Hercelin B, Mazza M (1991) Determination of 2-mercaptopropionylglycine and its metabolite 2-mercaptopropionic acid in plasma by ion-pair RP-HPLC with post-column derivatization. J Chromatogr 564:258-265 t0. Netter R Bannwarth B, PereR Nicolas A (1987) Clinical p harmacokinetics of D-penicillamine. Clin Pharmacokin 13:31%333 11. Chiba T, Kito H, ~lbshioka N (1973) Studies on thiol and disulfide compounds. I: Absorption, distribution, metabolism and excretion of 35S-2-mercaptopropionylglycine. Yakugaku-Zasshi 93: 112-118 12. Martensson J, Denneberg T, Kagedal B (1986) 2-mercaptopropionate, a novel metabolite formed during treatment with 2-mercaptopropionylglycine in cystinuria. Eur J Clin Pharmacol 31: 119-121 13. Fournier PE (1976) Tiopronin tablets: study of plasmatic levels and urinary excretion. Clinica: 423-428 14. Springolo V, Bertani W, Coppi G (1982) HPLC determination of 2-MPG in urine. J Chromatogr 232:456-460 15. Kagedal B, Carlsson M, Denneberg T (1986) Determination of 2-MPG in plasma and urine by HPLC. J Chromatogr 380: 301311 16. Carlsson MS, Denneberg T, Emanuelsson B, Kagedal B, Lindgren S (1990) Pharmacokinetics of I.V. 2-MPG in man. Eur J Clin Pharmaco138:49%503
Dr. B. Hercelin Pharmacokinetics/Biopharmacy Laboratoires Cassenne 17 rue de Pontoise F-95520 Osny, France
© Springer-Verlag 1992
The pharmacokinetics of tiopronin and its principal metabolite (2-mercaptopropionic acid) after oral administration to healthy volunteers B. Hercelin 1, E Leroy 2, A. Nicolas 2, C. Gavriloff2, D. Chassard 3, J.-J.Th~bault 3, M.T. Reveillaud 4, M.-E Salles 4, and ENetter 5 Unit4 de Pharmacocinrtique-Biopharmacie, Laboratoires Cassenne, 95520 Osny, 2Laboratoire de Chimie Analytique, Centre National de la Recherche Scientifique, Unit6 de Recherche Associde 597, Facult6 de Pharmacie, B. P. 403, 54001 Nancy Cedex, 3Aster, H6pital Cognacq-Jay, 15 rue E. Millon, 75015 Paris, 4Laboratoires Cassenne, Tour Roussel-Hoechst, 92080 Paris La Drtense, and 5Laboratoire de Pharmacotogie, Centre National de la Recherche Scientifique, Unit6 de Recherche Associre 1288, Facult6 de M6decine, 54505 Vandoeuvre-Les-Nancy Cedex, France Received: July 1, 1991/Accepted in revised form: January 15,1992
Summary. We have studied the pharmacokinetics of tiopronin and its principal metabolite, 2-mercaptopropionic acid (2-MPA) in healthy volunteers after the oral administration of 500 mg (2 Acadione ® tablets), followed by simultaneous assay of the two compounds in plasma over a period of 48 h using a new method (emission of fluorescence after H P L C and post-column derivatization by pyrene-maleimide). The absorption of tiopronin was slow (tmax between 4 and 6 h) and the plasma concentrations subsequently fell biexponentially. The principal metabolite 2-MPA appeared later in the plasma (tmaxbetween 10 and 12 h after a tag-time of 3 h) then disappeared monoexponentially. About 15 % of the tiopronin was metabolized to 2-MPA.
12, 24, and 48 h after administration. The plasma was separated immediately and frozen at - 70 °C within 20 rain. After thawing of the plasma samples, precipitation of proteins, and reduction by tributylphosphine, tiopronin and 2-MPA were assayed by liquid chromatography. Separation was achieved on a reversed-phase column by ionpairing with cetrimonium bromide. Post-column derivatization with a selective thioI reagent, pyrenemaleimide, was performed and the corresponding derivatives were monitored by fluorometry [9]. The method included an initial reduction of the disulphide bonds; the plasma concentrations obtained therefore rigorously corresponded to (a) all of the circulating molecules reducible to tiopronin and (b) all of the circulating molecules reducible to 2-MPA. The limits of detection of the assay were 0.1 gg-ml-1 for tiopronin and 0.02 gg.ml ! for 2-mercaptopropionic acid. The pharmacokinetics were calculated by means of standard methods (linear trapezoidal method, linear regression of the termi-
Key words: Tiopronin, 2-mercaptopropionic acid; pharmacokinetics, healthy volunteers CH3-CH-CO-NH-CH2-COOH
]
i
Tiopronin, or 2-mercaptopropionylglycine (2-MPG), is a thiol derivative which has been used for several years in patients with cystine stones and also more recently in the long-term treatment of rheumatoid arthritis [1-8]. Tiopronin is structurally similar to D-penicillamine (Fig. 1). Data on the in vivo fate of tiopronin are recent and limited, because of analytical difficulties. Our objective was therefore to evaluate the pharmacokinetics of tiopronin and its prinicpal metabolite, 2-mercaptopropionic acid, in healthy volunteers, using a specific and sensitive assay for the two compounds.
SH 2-mercaptopropionylglycine, 2-MPG, tiopronin j \
/
Moderate oxidation
/
i Disulphide bonds - symmetrical asymmetrical
\
i
Strong oxidation
Hydrolysis
\
Sulphoxide Sulphone etc.
(2S-HpA)
]
/\ Methods After approval from the Ethics Committee of H6pital Cognacq-Jay in Paris, t2 consenting male Caucasian volunteers, mean age 23 (19 to 31) y and mean weight 73 (58 to 89) kg took a single oral dose of 500 mg of tiopronin as two tablets of Acadione®(Laboratoires Cassenne, France), containing 250 mg of the active substance, with 100 ml of water. Blood samples from each subject were collected in EDTAcoated vials just before administration and at 1, 2, 3, 4, 4.5, 5, 6, 8, 10,
Moderate oxidation
Strong oxidation
IDisulphide bonds
Sulphoxide1 Sulphone ]
/
\
Fig. 1. The chemical structure of tiopronin and the possible routes of its metabolism
94 10~0 ~Z~ZZ~ZZ:Z?2ZZZZZ~Zi~ZZZZZZ~ZZZZ-ZZZ~Z~2~ZZZZ~Z2~Z~ZZ~Z~Z~ZZ~ZZ~Z~ZZZZ2~
i...................
170 i:Z::
~. . . . . . . . . . . . . . . . . . . . . . . . . . . .
. ...........................
i ................................
~. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
i
beyond) Z:=;ZZZZTZZE:2::EZZZZZZZ2ZZZZZZ~ZZZZZ,ZZZZZZZZ::2iZZZZZZZZEZZZZZ i
:.......................
i................................!..................................i.............................i
8
N
0,01
0
10
20
30
40
50
Time ( h )
Fig.2. Mean plasma concentrations of tiopronin ( • ) and 2-MPA (O) after oral administration of 500 mg of tiopronin to 12 healthy volunteers
nal part of the log concentration versus time curve, etc) using a specificprogram created with Lotus 1-2-3;mean values, standard deviations (n-l), and coefficients of variation were calculated for each measurement. Results The time-courses of the mean concentrations of tiopronin and 2-MPA are illustrated in Fig. 2. The pharmacokinetic results are presented in Table 1. Discussion
Plasma concentration measurements The determination of tiopronin in biological media presents certain difficulties for various reasons. First, as for Dpenicillamine, the assay of well-defined chemical entities is altered by the presence of endogenous molecules with similar analytical behaviour and by the probable existence of steady states between unconjugated tiopronin and various possible conjugated forms; second, the molecule is exTable 1, The pharmacokinetics of tiopronin and 2-MPA after oral administration of 500 mg to healthy volunteers Tiopronin
2-MPA
mean (SD) (n) mean (SD) (n)
lag time t~ Cmax tle2.x, ha~ AUC AUCo~/AUC MRT
posed in vivo to metabolism via several pathways, some of which are more or less reversible (e.g. oxidation with formation of disulphide bonds), while others are irreversible (e. g. hydrolysis of the amide group with the formation of 2-mercaptopropionic acid, oxidation to sulphoxide and
(h) (h) (gg. ml-') (h) (h) (gg.ml-I h) (%) (h)
(0.3) (0.7) 3.6 (0.8) 2.4 (0.8) 18.7 (10.3) 29.0 (10.7) 90.5 (9.3) 11.2 (2.0) 0.6
5.0
(12) 2.7 (12) 10.8 (12) 0.22 (Ii) (10) 7.6 (II) 3.5 (11) 97.1 (12) 18.4
(1.9) (12) (1.3) (12) (0.09)(12) (4.2) (10) (1.2) (i0) (5.9) (10) (3.6) (12)
[11,121
(Fig. 1).
Tiopronin was first assayed in plasma by direct polarography of dilute plasma in 1976 [13]; this technique lacked specificity, being unable to distinguish tiopronin from other circulating thiols. A new assay, using liquid chromatography and detection by UV absorption of the derivative obtained by reaction with furoyl chloride, was described in 1982 [14]. This method was suitable for assay" in aqueous solutions or urine, but its sensitivity was too low to measure plasma concentrations after the administration of a therapeutic dose of tiopronin. More recently, a specific and more sensitive method has been described using liquid chromatography of tiopronin followed by fluorescence detection after precolumn derivatization by N-(7-dimethylamino-4-methyl3-coumarinyl)-maleimide (DACM) [15]. The technique used in this study was based on the same principle, but used post-column pyrene-maleimide derivatization. The specificity was sufficient for the two wincipal chemical entities present, tiopronin and 2-MPA, to be analysed simultaneously. The limits of detection also allowed precise and complete description of the pharmacokinetics of the two substances.
The pharmacokinetics of tiopronin after oral administration After a lag time of about 0.5 h, tiopronin appeared in the circulation with a Cmaxof 3-4 gg' ml ~ at a tmax of 4-6 h. These results show that the absorption of the tiopronin from the gastrointestinal tract is slow; they are also in agreement with the results reported by Kagedal et at. [15] in 5 subjects. The plasma concentrations then fell biexponentially with half-lives of about 2.4 and 15-30 h. In other subjects, using a slightly different assay method, Carlsson et al. obtained similar values after the intravenous administration of 250 mg of tiopronin and mathematical smoothing of the curves, with half-lives of about 2 and 55 h [16]. The mean residence time of tiopronin was around 11 h.
Pharmacokinetics of the principal metabolite 2-MPA 2-mercaptopropionic acid appeared in the circulation with a tmaxof 10-12 h after a lag time of about 3 h. The subsequent elimination was monoexponential with a half-life of 4-12 h. The mean residence time of the metabolite was slightly longer (15 to 22 h) than that of tiopronin. The values of A U C for tiopronin and 2-MPA showed that 10-15 per cent of tiopronin was metabolized to 2-MPA. The low plasma concentrations of tiopronin during the terminal phase, the small fraction of the total A U C to which it contributes, and the mean residence time (about
95 11 h) suggest that the risk of a c c u m u l a t i o n during rep e a t e d dosing is m o d e r a t e and that twice daily administration is justified. T h e r e is no risk of a c c u m u l a t i o n of 2 - M P A in the b o d y during long-term treatment.
Acknowledgements. The authors are very grateful to Mrs G Veniger and Mrs MThenier for their invaluable assistance in the preparation of this paper.
References 1. Crossley M J, Spowage M, Hunneyball IM (1987) Studies on the effects of pharmacological agents on the antigen-induced arthrifts in balb/c mice. Drug Exp Clin Res 13:273--277 2. Amor B, Mdry C, De Gery A, Zizi M (1986) Tiopronin and rheumatoid polyarthritis. Rev Rhum Mal Osteoartic 53:39-43 3. Amor B, M6ry C, De Gery A (1988) Acadione, a new long-term treatment of rheumatoid polyarthritis. Rev Rhum Mal Osteoartic 55:462--466 4. Sigaud M, Mangars Y, Maisonneuve H, Prost A (1988) Tiopronin in 69 cases of rheumatoid polyarthritis pretreated by D-penicillamine. Rev Rhum Mal Osteoartic 55:467-471 5. Mordini M, Guidoni G, Maestrini M, Buonavia A, Lavagni A (1989) Basic treatment of rheumatoid arthritis with tiopronin: a study of 25 cases. Minerva Med 80:1019-1023 6. Delecoeuillerie G (1989) Tolerance and efficacy of tiopronin, a new long-term treatment of rheumatoid polyarthritis. Rev Rhum Mal Osteoartic 56:38-42 7. Ferraccioli GF, Salaffi F, Nervetti A, Manganelli P (1989) Longterm outcome with gold thiosulfate and tiopronin in 200 rheumatoid patients. Clin Exp Rheumatol 7:577-581 8. Sany J, Combe B, Verdie-Petibon D, Tagemouati A, Daures JP (1990) Study of the tolerance of ftopronin (Acadione) in long-
term treatment of rheumatoid polyarthritis. Rev Rhum Mal Osteoartic 57:105-111 9. Leroy R Nicolas A, Gavriloff C, Matt M, Netter R Bannwarth B, Hercelin B, Mazza M (1991) Determination of 2-mercaptopropionylglycine and its metabolite 2-mercaptopropionic acid in plasma by ion-pair RP-HPLC with post-column derivatization. J Chromatogr 564:258-265 t0. Netter R Bannwarth B, PereR Nicolas A (1987) Clinical p harmacokinetics of D-penicillamine. Clin Pharmacokin 13:31%333 11. Chiba T, Kito H, ~lbshioka N (1973) Studies on thiol and disulfide compounds. I: Absorption, distribution, metabolism and excretion of 35S-2-mercaptopropionylglycine. Yakugaku-Zasshi 93: 112-118 12. Martensson J, Denneberg T, Kagedal B (1986) 2-mercaptopropionate, a novel metabolite formed during treatment with 2-mercaptopropionylglycine in cystinuria. Eur J Clin Pharmacol 31: 119-121 13. Fournier PE (1976) Tiopronin tablets: study of plasmatic levels and urinary excretion. Clinica: 423-428 14. Springolo V, Bertani W, Coppi G (1982) HPLC determination of 2-MPG in urine. J Chromatogr 232:456-460 15. Kagedal B, Carlsson M, Denneberg T (1986) Determination of 2-MPG in plasma and urine by HPLC. J Chromatogr 380: 301311 16. Carlsson MS, Denneberg T, Emanuelsson B, Kagedal B, Lindgren S (1990) Pharmacokinetics of I.V. 2-MPG in man. Eur J Clin Pharmaco138:49%503
Dr. B. Hercelin Pharmacokinetics/Biopharmacy Laboratoires Cassenne 17 rue de Pontoise F-95520 Osny, France
