Comparison of the serum and tissue concentrations of cefuroxime from cefuroxime axetil and phenoxymethylpenicillin in patients undergoing tonsillectomy.

In the study described, the pharmacokinetics of two oral betalactams, cefuroxime axetil and phenoxymethylpenicillin, were compared with respect to their penetration into tonsil tissue. Seventeen patients were given cefuroxime axetil 500 mg single dose and 16 patients were given phenoxymethylpenicillin 650 mg single dose, at different time intervals before tonsillectomy. The tonsils were freeze-dried and the drug concentrations in serum and tissue determined by a high performance liquid chromatographic method. Cefuroxime axetil showed a slightly better penetration ratio (mean 35%, median 32%) than phenoxymethylpenicillin (mean 31%, median 24%) however the difference was not statistically significant. The bioavailability of cefuroxime axetil was low due to being administered in the fasting state. The relatively low penetration ratios of both drugs into samples of whole tissue can be explained by the localization of betalactam antibiotics primarily in the extracellular fluid, with low penetration into normal cells. Both drugs were found to reach concentrations in tonsil tissue above the minimum inhibitory concentration for Group A beta-haemolytic streptococci after a single oral dose. In addition to streptococci, Haemophilus influenzae and beta-lactamase producing Staphylococcus aureus were isolated in a significant number of the tonsils. These bacteria may play a pathogenic role, but this was not investigated.