Absorption of phenoxymethylpenicillin from mixtures and tablets in healthy volunteers

The absorption of the potassium, calcium and benzathine salts of phenoxymethylpenicillin, given as mixtures, was investigated in twelve healthy volunteers. The potassium salt gave the fastest and highest serum peak levels. Also the relative bioavailability of the potassium salt was greatest, as indicated by the areas under the serum concentration/time curves (AUC). In a second study with twelve other volunteers, the absorption of the mixtures and tablets of the potassium salt was studied. The peak serum levels and AUC were comparable after these preparations. The results in our two studies indicate that, from a pharmacokinetic point of view, the potassium salt of phenoxymethylpenicillin in mixtures should be preferred in clinical practice. It also appears that the absorption of phenoxymethylpenicillin from the tablets and mixtures of the potassium salt is comparable, giving the same relative bioavailability.