Pharmacokinetics of intravenous imipenem/cilastatin during intermittent haemofiltration

The pharmacokinetics of a single iv dose of imipenem/cilastatin (500/500 mg) were studied during and after intermittent haemofiltration (IHF) treatment in six patients with chronic renal failure. The elimination half-lives of imipenem and cilastatin during the IHF treatment were almost identical, 1.4 +/- 0.3 and 1.5 +/- 0.3 h, respectively. Accordingly, approximately 75% of the given dose was eliminated during a 3-h IHF session. However, there was a great difference between the elimination half-lives of the two drugs in the post-treatment period, 3.4 +/- 1.0 and 16 +/- 10 h for imipenem and cilastatin, respectively. The haemofiltration clearance of imipenem was 134 +/- 41 ml/min and that of cilastatin 109 +/- 8 ml/min. On the basis of our results, we suggest that a supplementary dose of imipenem/cilastatin (500/500 mg) should be given directly after the IHF treatment. This dose should be the starting dose for a period of 12-h dosing intervals until the next IHF procedure.