The synthesis of the acetoxymethyl (AOM) ester of cefamandole (CM) is described. The sparingly soluble ester is shown to be well absorbed orally by mice, but only when administered in solution in a partially non-aqueous vehicle, 50% propylene glycol. Neither the ester in aqueous suspension nor the sodium salt of CM in solution is well absorbed orally. The rate of oral absorption of the ester from solution is very rapid as shown by the early peak time and
shape of the plasma level curve. Oral bioavailability from solution is at least 60% and is apparently limited only by hydrolysis or precipitation of a variable portion of the ester dose in the intestinal lumen prior to absorption.