Steady-state pharmacokinetics of ipriflavone and its metabolites in patients with renal failure.

Ipriflavone is a recently introduced anti-osteoporotic agent extensively metabolized to four major metabolites (M1, M2, M3, M5). Its pharmacokinetics, after repeated doses of the drug, was investigated in patients with renal failure and compared with those of healthy volunteers. Plasma levels at steady-state of the unchanged drug, and its metabolites M1, M2 and M5 were higher in the patient group, with the presence of secondary peaks, which could be explained by the biliary excretion of the substances. Evaluation of renal elimination in patients in respect to healthy volunteers was performed by a "relative renal elimination index". The index decreased with the increase of renal disease mainly when the renal failure was moderate to severe.