Single-dose pharmacokinetic study of 900 mg fenbufen in the elderly.

A single oral dose of fenbufen 900 mg was administered to 12 elderly volunteers, average age 81 years. The plasma levels of fenbufen and its major metabolites were measured at intervals over 72 hours following dosing. Results were compared with previously obtained data from young healthy volunteers. No significant differences were seen, after corrections from body weight, between the two groups for fenbufen and 2 of its metabolites. The mean serum levels in the elderly of biphenylacetic acid were significantly higher at 36 hours and 48 hours than the means at these times in the young group. This was not thought to be clinically significant. The terminal half lives for fenbufen and its major metabolites were not significantly prolonged compared with young volunteers.