Pharmacokinetics of meropenem in patients with cystic fibrosis

The pharmacokinetics of meropenem were studied after single i.v. infusions of 15 mg meropenem/kg body weight in eight subjects with cystic fibrosis (C F) and eight healthy volunteers matched for age, sex, and weight. Significa ntly shorter terminal half-fives (mean, 0.74 h vs. 0.99h) and mean residenc e times (mean, 1.09 h vs. 1.39 h) were noted in CF subjects. Plasma and ren al clearances tended to be higher and distribution volumes smaller among th e patients, but differences were not statistically significant. The results are consistent with the findings for many other betalactam agents used in CF patients. Assuming a MIC90 of 4 mg/l for meropenem against Pseudomonas a eruginosa, the time above the MIC was less than 3.3 h in six of the eight C F patients. This finding should be kept in mind when designing treatment re gimens with meropenem in CF subjects.