A method for enhancing the oral bioavailability of a prodrug ester by formulating the ester as a non-emulsified formulation with lecithin; as well as a pharmaceutical composition of at least one antibiotic and lecithin in a non-emulsified formulation; a method of treating infections with the non-emulsified formulation, and a method for preparing tablets by direct compression of blends of drugs with lecithin are disclosed. Non-emulsified formulations include solids, tablets, capsules, lozenges, suspensions, elixirs and solutions, and exclude emulsions, liposomes, lipid matrix systems and micro-emulsions. A suitable prodrug ester is a cephalosporin β-lactam antibiotic such as cefditoren pivoxil, and a suitable non-emulsified formulation is a solid formulation.