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

Abstract

1. Pipemidic acid in bacteriological screening was more potent than nalidixinic acid, notably against Pseudomonas.

2. 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: t_max, 2.3 h; C_max, 3.3 μg/ml; t_1/2,4.6 h; V_ares, 2.041/kg; Cl_tot 5-48 ml/min per kg; Cl_ren, 3.05 ml/min per kg; A_e^0-24, 55.7% of dose.

3. In elderly inpatients with normal renal function, the main alterations from middle-aged volunteers were: slightly elevated C_max (+ 28%) and AUC (+ 13%) and significantly decreased V_area (-51%), Cl_ren (-34%) and A_e^0-24 (-31%).

4. In elderly inpatients with renal insufficiency, Cl_ren (— 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.

5. Among all the subjects, there was a negative correlation between Cl_creat and AUC^0-∞, and a positive correlation between Cl_creat and Cl_tot, and A_e^0-24.

6. In the treatment of urinary-tract infections with pipemidic acid, a mild renal insufficiency (Cl_creat 30 ml/min or more) does not necessitate dose adjustments.