Concentration of penicillin in nasopharyngeal secretions

The penicillin concentration in the nasopharyngeal secretion after penicillin administration was studied in 33 patients undergoing tonsillectomy. Benzylpenicillin was either administrated by the intravenous or the intramuscular route in doses of 0.6-1.2 g. Phenoxymethylpenicillin was given perorally in doses of 0.5-1.0 g. The secretion from the nasopharynx was collected prior to the operation both in a disposable collector and on a filter paper disc. A serum sample was also drawn prior to and immediately after the operation. The serum penicillin concentration reached levels of 16.0 mg/l, 5.8 mg/l and 3.6 mg/l (mean values) when given by the intravenous, the intramuscular and the peroral route, respectively. The mean penicillin concentration in nasopharyngeal secretion was 1.6 mg/l, 0.3 mg/l and 0.3 mg/l for these three administration modes. In the majority of cases the concentration of penicillin in the nasopharyngeal secretion exceeded the minimum inhibitory concentration for Streptococcus pneumoniae (0.006-0.12 mg/l).