Effect of Various Ophthalmic Ointment Bases on Carbenicillin and Gentamicin Release

Abstract

A microbiological agar plate method has been used for comparatively measuring the release of each carbenicillin and gentamicin from eighteen ointment bases for possible ophthalmic use. A significant difference in the antibiotic releasing ability of the various bases was observed. No one base was found to be consistently superior with each antibiotic tested. All the eight best bases, except one base, were composed of castor oil gelled by hydrogenated castor oil, Aerosil or white wax and may contain cetyl alcohol, Span 80, Span 40, wool alcohols, glyceryl monostearate and cetostearyl alcohol as wetting and spreading agents.