Pharmacological studies with lincomycin in late pregnancy.

The placental transmission of lincomycin was studied in 60 patients in late pregnancy. A peak maternal blood level of 12.5 mug/ml was recorded 45 minutes after injection, and detectable levels were still present up to 42 hours after a single injection. A peak cord blood level of 2.7 mug/ml was recorded 55 minutes after injection; cord blood levels were about a quarter of the maternal blood levels, and in most cases no levels were detectable 24 hours after a single injection. The passage of lincomycin into and out of the liquor was slower and more variable, but some hours after injection the liquor levels were always higher than the maternal or cord blood levels, and detectable levels were still present in the liquor 52 hours after a single injection. Repeated injections did not lead to any significant accumulation of lincomycin. The only side effect was a possible case of neuromuscular block in a mother delivered by caesarean section. No infant was adversely affected.