Pharmacokinetics of Phenoxymethylpenicillin in Volunteers

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Abstract
Pharmacokinetics of phenoxymethylpenicillin was studied in 12 healthy volunteers. They received 4 different single oral dose sizes. At all dose levels (0.4, 1, 2 and 3 g) phenoxymethylpenicillin was rapidly absorbed, usually with serum peaks within 0.75 h. The mean maximal serum peak (.+-. SD) were 6.1 .+-. 2.0, 15.0 .+-. 4.3, 26.3 .+-. 10.0 and 35.5 .+-. 10.8 mg/l after 0.4, 1, 2 and 3 g, respectively. The relationship between the mean peak serum concentrations and the doses was nonlinear (P < 0.001). The mean areas under the serum concentrations vs. time curve (AUC) increased almost linearly with increasing doses and the deviation from linearity was not significant (P < 0.05). Very low penicillin concentrations were obtained in saliva. The urinary excretion during 10 h was 37-43% of the doses given. The pharmacokinetic results indicated that phenoxymethyl penicillin in the present formulation is rapidly and well absorbed up to as high doses as 3 g. The tablet formulations used were better absorbed than previous ones. The percent of absorption was relatively lower with the highest doses, but this probably has only minor therapeutic consequences.