Three groups of rabbits received bilateral 100-mg subconjunctival injections of potassium, procaine, or benzathine penicillin G. A fourth group received similar injections of a compound containing all three penicillin salts. Aqueous was withdrawn and bioassayed for antibiotic activity at varying periods of time following subconjunctival injections.
Potassium penicillin produced very high intraocular antibiotic levels which declined rapidly and were no longer present 24 hours after injection. Procaine penicillin resulted in high intraocular drug concentrations which were present only in trace amounts at 24 hours. Benzathine penicillin failed to produce an effective intraocular antibiotic concentration at any time. The compound containing all three penicillin salts produced high penicillin titers in rabbit aqueous which fell to below therapeutically effective levels by 24 hours.
Records RE. Subconjunctival Injection of the Repository PenicillinsA Comparative Study of the Intraocular Penetration. Arch Ophthalmol. 1967;78(3):380-383. doi:10.1001/archopht.1967.00980030382022