Bioavailability of paediatric mixtures containing phenoxymethylpenicillin calcium or potassium salt

The bioavailability of the calcium and potassium salts of phenoxymethyl-penicillin (dose 38,000 I.U./kg) was investigated in eight healthy adult volunteers. Administration of the calcium salt as an aqueous oral mixture resulted in a mean peak plasma concentration of 8.52 mg/l (SD 1 X 96) and that of the potassium salt mixture in a concentration of 8.40 mg/ml (SD 2.61), p greater than 0.1. The median time-to-peak levels were 0.75 h and 1.0 h, respectively (p greater than 0.1). The mean AUC for the calcium salt mixture was 16.94 mg X h/l (SD 3.31) and for the potassium salt 15.84 mg X h/l (SD 4.76), p less than 0.09. These findings confirm that an aqueous mixture of calcium phenoxymethylpenicillin is equivalent to a mixture of potassium phenoxymethylpenicillin.