Cloxacillin Distribution in the Rabbit Eye After Intravenous Injection

Abstract

Distribution of isotopically labelled and intravenously injected cloxacillin was studied in rabbit eye. The antibiotic concentration determined by liquid scintillation counting proved to be a reliable measure of the total antibiotic concentration when controlled by microbiological assay. In the rabbit eye after an intravenous injection of 50 mg/kg of cloxacillin sodium, longlasting antibiotic concentration regarded as therapeutic against penicillinase producing staphylococci was obtained in all vascularized ocular structures and in the cornea. The antibiotic present in the iris and ciliary body, and in the retina and choroid preparations, proved to be partly intravascular, whereas it penetrated better into the extravascular tissue compartment of the sclera and limbal area. Cloxacillin failed to achieve a therapeutic antibiotic concentration in the vitreous body and in the lens. Administration of probenecid had an enhancing effect on ocular cloxacillin concentration allowing improved drug diffusion into the eye by means of an elevated plasma concentration. No specific ocular effect of probenecid was noticed. Therapeutic concentration of cloxacillin in the aqueous humour, otherwise barely achieved, was more satisfactorily obtained with a previous injection of probenecid.

Effect of Paracentesis on Ocular Cloxacillin Concentration

“…The correlation between radioactivity and microbiologically determined antibiotic concentration are presented in a previous paper (Salminen 1978).…”

“…Preparation and radioassay of plasma and ocular samples, microbiological assay of plasma and statistics were done as previously described (Salminen 1978).…”

Ampicillin Penetration Into the Rabbit Eye

“…They were both eyes of four rabbits killed at 150, 180 and 210 min. The dissection of the frozen eyes, liquid scintillation counting of plasma and ocular samples, microbiological assay of plasma and statistical analysis of the results were carried out mainly as described previously (Salminen 1978).…”