[Pharmacokinetics of intramuscular mezlocillin in patients with normal and impaired renal function (author's transl)].

Pharmacokinetic values of mezlocillin were determined after a single intramuscular injection of 1 g to 10 subject with normal renal function, 10 patients with stable renal insufficiency and 5 patients with chronic renal failure under long-term haemodialysis. The values obtained in normal subjects were : biological half-life Tb 1/2 0.9 hour; elimination constant Ke 0.790 (h-1); total clearance Ct 449 ml/min/1.73 m2; renal clearance Cr 263 ml/min/1.73 m2. Twelve hours after the injection 72.2 % of the dose administered were recovered in the urine. Theoretical values after repeated injection were calculated from the values obtained in subjects with normal renal function. The loading doses providing steady state serum concentrations were determined for various dosage intervals (2, 3, 4, 6 and 8 hours). In patients with renal insufficiency or treated with haemodialysis, serum levels decreased more slowly. The theoretical Tb 1/2 for zero creatinine clearance was 4.7 hours. Sixty-two percent of the amount of mezlocillin present in the central compartment at the onset of haemodialysis were removed after a 6-hour dialysis session. In all 25 subjects investigated, a significant correlation was found between Ke and Ccr (Ke = 0.1973 + 0.0046 Ccr). This correlation was used to calculate the loading and maintenance doses (and sometimes also the intervals between injections) adjusted to renal function values. Dosage guidelines in relation to the renal function were established from these data.