CLINICAL PHARMACOKINETICS OF MEROPENEM AFTER THE FIRST AND 10TH INTRAMUSCULAR ADMINISTRATION

We investigated the pharmacokinetics of meropenem after the first and tenth im administration in patients with respiratory tract infections. Ten patients (mean age 63.8 +/- 5.2 years) received meropenem 500 mg tds for at least ten doses, and plasma and urine antibiotic concentrat ions were determined by microbiological assay. After the first injecti on a mean peak plasma concentration of 7.93 +/- 1.29 mg/L was observed at 1 h. Trough levels at 8 h (0.29 +/- 0.16 mg/L) were detectable in five of ten treated patients. The mean terminal half-life was 1.08 +/- 0.2 h with an area under the curve (AUG) value of 23.8 +/- 4.59 mg/L. h, and a cumulative urinary recovery at 8 h of 48.43 +/- 3.12%. There was no evidence of change in the pharmacokinetics of meropenem after r epeated im administration, though the mean peak plasma concentration a nd AUC value were slightly increased. The accumulation ratio (assessed using AUC values) was 1.18 +/- 0.19 after multiple doses and was cons idered to be of little kinetic and clinical importance. Moreover, many of the trough concentrations of meropenem were below the limit of det ection of the assay. After im administration meropenem concentrations exceeded 0.5 mg/L for longer than previously described following iv in fusion. No adverse events were reported.