The pharmacokinetics of mecillinam and pivmecillinam in pregnant and non‐pregnant women.

1. The pharmacokinetics of parenteral mecillinam (n = 27) and oral pivmecillinam (n = 12) were studied in pregnant (n = 27) and non‐ pregnant (n = 12) subjects. 2. In early pregnancy (9‐14 weeks of gestation) the mean peak plasma drug concentration (Cmax = 19 +/‐ 9 micrograms ml‐1) after an intravenous injection of 200 mg mecillinam was significantly lower (P less than 0.05) and the volume of distribution (V = 49 +/‐ 20.1) significantly larger (P less than 0.05) than in non‐pregnant subjects (Cmax = 35 +/‐ 18 micrograms ml‐1, V = 29 +/‐ 12.1). In late pregnancy (39‐40 weeks of gestation) the plasma mean peak concentration (Cmax = (29 +/‐ 14 micrograms ml‐1) after parenteral administration of 200 mg mecillinam was slightly lower and the volume of distribution (V = 65 +/‐ 29.1, V = 0.9 +/‐ 0.4 l kg‐1) significantly larger than that in non‐pregnant subjects (V = 0.4 +/‐ 0.3 l kg‐1). Also after oral administration of 200 mg pivmecillinam, equimolar to 136.5 mg mecillinam, the mean peak plasma concentration in pregnant subjects (Cmax = 1.8 +/‐ 1.2 micrograms ml‐1) was slightly lower than that in non‐pregnant subjects (Cmax = 1.7 +/‐ 1.2 micrograms ml‐1). 3. The mean half‐life of elimination after parenteral administration of mecillinam was significantly longer during both early (t1/2,Z = 133 +/‐ 38 min, P less than 0.05) and late pregnancy (t1/2,Z = 107 +/‐ 41 min, P less than 0.05) as compared with the non‐pregnant state (t1/2,Z = 75 +/‐ 21 min).(ABSTRACT TRUNCATED AT 250 WORDS)

DOI: 10.1111/j.1365-2125.1992.tb04092.x

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