THE PHARMACOKINETICS OF TIOPRONIN AND ITS PRINCIPAL METABOLITE (2-MERCAPTOPROPIONIC ACID) AFTER ORAL-ADMINISTRATION TO HEALTHY-VOLUNTEERS

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(R) 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 HPLC and post-column derivatization by pyrene-maleimide). The absorption of tiopronin was slow (t(max), between 4 and 6 h) and the plasma concentrations subsequently fell biexponentially. The principal metabolite 2-MPA appeared later in the plasma (t(max) between 10 and 12 h after a lag-time of 3 h) then disappeared monoexponentially About 15 % of the tiopronin was metabolized to 2-MPA.