Pharmacokinetics of pipemidic acid in healthy middle-aged volunteers and elderly patients with renal insufficiency.

Pipemidic acid in bacteriological screening was more potent than nalidixinic acid, notably against Pseudomonas. In a study in middle-aged female volunteers, the relative bioavailability of a single 500 mg tablet of pipemidic acid was good. The main pharmacokinetic parameters were: tmax, 2.3 h; Cmax, 3.3 micrograms/ml; t1/2, 4.6 h; Varea, 2.04 l/kg; Cltot, 5.48 ml/min per kg; Clren, 3.05 ml/min per kg; Ae(0-24), 55.7% of dose. In elderly inpatients with normal renal function, the main alterations from middle-aged volunteers were: slightly elevated Cmax (+28%) and AUC (+13%) and significantly decreased Varea (-51%), Clren (-34%) and Ae(0-24) (-31%). In elderly inpatients with renal insufficiency, Clren (-58%) was decreased compared with elderly inpatients with normal renal function. Concn. of pipemidic acid in urine still exceeded several-fold the MIC values of the most pathogenic bacteria. Among all the subjects, there was a negative correlation between Clcreat and AUC0-infinity, and a positive correlation between Clcreat and Cltot, Clren and Ae(0-24). In the treatment of urinary-tract infections with pipemidic acid, a mild renal insufficiency (Clcreat 30 ml/min or more) does not necessitate dose adjustments.