The pharmacokinetics of albumin conjugates of D-penicillamine in humans.
D-penicillamine (D-PEN) is incompletely recovered during short-term balance studies, despite rapid elimination of D-PEN and its low molecular weight metabolites. Urinary excretion of metabolites of D-PEN also persists long after cessation of chronic therapy. A study was performed to determine whether the formation and later breakdown of a stable disulfide between D-PEN and plasma albumin could explain these aspects of D-PEN pharmacokinetics. Five human volunteers received D-penicillamine, 250 mg orally, daily for 21 days. Plasma concentration-time profiles for D-PEN and D-PEN-albumin disulfide (D-PEN-albumin) were determined during the first day and pre-dose concentrations were measured on five further occasions. The pharmacokinetics of D-PEN on the first day were similar to those reported previously. No D-PEN was found in any of the pre-dose specimens. The concentration of D-PEN-albumin rose rapidly during the first day, with an estimated 8.6% of the bioavailable D-PEN being transformed to D-PEN-albumin. Pseudo-steady-state concentrations of D-PEN-albumin were achieved in three subjects at between 14 and 21 days. The mean trough concentration of D-PEN-albumin at 21 days (19.5 microM) exceeded the peak concentration of D-PEN (during the first day) by 5.7-fold. The terminal elimination half-life of D-PEN-albumin was 1.65 +/- 0.29 days, which compared with an elimination half-life of 59 +/- 8.4 min for D-PEN.(ABSTRACT TRUNCATED AT 250 WORDS)
Department of Clinical Pharmacology and Toxicology, St Vincent's Hospital, Australia.
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Joyce
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Day
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Murphy
D000328:Adult; D000418:Albumins; D001682:Biological Availability; D002851:Chromatography, High Pressure Liquid; D005260:Female; D006207:Half-Life; D006801:Humans; D008297:Male; D008954:Models, Biological; D010396:Penicillamine / Q000378:metabolism / Q000493:pharmacokinetics*
D000418:Albumins; D010396:Penicillamine