Concentration of phenoxymethylpenicillin in tonsillar tissue

Seventeen patients underwent tonsillectomy 55-120 min after receiving oral phenoxymethylpenicillin 12.5 mg/kg bodyweight. The penicillin concentration in serum and tonsillar tissue in each patient was determined by a microbial assay. In 9 patients with tonsillar hyperplasia, but with no prior history of tonsillitis, the mean penicillin concentration in serum and in tonsillar tissue was 5.0 mg.l-1 and 1.32 mg.g-1, respectively, and in 8 patients with manifest tonsillitis the corresponding values were 3.01 mg.l-1 and 0.67 mg.g-1. It appears that the penicillin concentration in tonsillar tissue is about 1/5 to 1/4 of that in serum, regardless of whether the tonsils are inflamed or hypertrophied.