[Studies on the transplacental passage of cefotaxime in late pregnancy].

The transplacental passage of a single intravenous dose of cefotaxime (CTX), 1,000 mg, was examined in 11 pregnant women undergoing delivery at term by cesarean section. The results were as follows. 1. Measurements by HPLC: After a single 1,000 mg intravenous dose, the maternal blood level of CTX took the following course: 40.1 +/- 3.4 mcg/ml (mean +/- S.E.) at 15 minutes, 22.5 +/- 1.9 mcg/ml at 30 minutes, 10.8 +/- 0.9 mcg/ml at 60 minutes and 3.2 +/- 0.4 mcg/ml at 120 minutes. Slightly high maternal blood levels of 0.7 and 1.1 mcg/ml were obtained at child deliveries made at 200 minutes, but only a trace amount was found at a child delivery at 356 minutes. The CTX level in the umbilical cord blood was comparatively high until the measurement at 222 minutes, and then declined. IN the amniotic fluid, peak levels were observed at 222 to 252 minutes, thereafter decreasing slowly. Desacetyl-CTX, a metabolite of CTX, showed maternal blood levels of 5.8 +/- 0.5 mcg/ml at 15 minutes, 6.3 +/- 0.6 mcg/ml at 30 minutes, 6.8 +/- 0.7 mcg/ml at 60 minutes and 4.9 +/- 0.7 mcg/ml at 120 minutes. Thus, the maternal blood level of desacetyl-CTX showed an increasing tendency until 60 minutes after intravenous administration, and decreased rapidly from 120 minutes onwards. No consistent tendency was noted in desacetyl-CTX levels in the umbilical cord blood and the amniotic fluid. 2. Measurements by bioassay: Maternal blood levels of CTX determined by bioassay were 45.2 +/- 3.3 mcg/ml at 15 minutes, 25.8 +/- 2.2 mcg/ml at 30 minutes, 12.4 +/- 1.0 mcg/ml at 50 minutes adn 4.0 +/- 0.5 mcg/ml at 120 minutes. At the time of child delivery, maternal blood levels of CTX were 1.1 and 2.6 mcg/ml at 200 minutes, and then decreased slowly. Trace levels were noted at 336 minutes and CTX was undetectable at 356 minutes. 3. The HPLC study demonstrated that the level of CTx remained comparatively high in the umbilical cord blood and the amniotic fluid even 6 hours after administration (0.3--0.4 mcg/ml and 4.0 mcg/ml, respectively). This result suggests, in consideration of CTX's MIC values for causative organisms, that CTX will produce a sufficient clinical effect in perinatal infections. No side effects were observed in the mothers or their babies.