[Relation between pharmacokinetics of an antibiotic in ocular fluids and the method of administration and dosage form of gentamycin]

Abstract

The experiments on rabbits with intraocular infection provided determination of the optimal route and regimen of gentamicin administration in various dosage forms. Gentamicin sulfate made in the USSR was used. It was shown that during instillations of 0.3 per cent eye drops, gentamicin did not penetrate into the intraocular fluid. The ophthalmic drug films (ODF) containing 0.5 mg gentamicin per film provided better penetration of the antibiotic into the eye cavity in the concentrations in the ocular fluid active only against the most gentamicin sensitive microbial strains. Therefore, the use of the ODF containing gentamicin may be recommended for the treatment of intraocular infections caused by gentamicin sensitive organisms. When the antibiotic was administered subconjunctively in a dose of 20 mg, its therapeutic concentrations were mainly detectable in the anterior chamber fluid. Therefore, the use of this administration route was first of all rational in intraocular infections of the anterior part of the eye. The antibiotic should be used in such cases at least twice a day. The therapeutic concentrations of gentamicin active against the majority of the microbial strains were attained in the vitreous body only on intravitreal administration. The high therapeutic levels of gentamicin in the vitreous body after its injection in a dose of 0.4 mg were recorded for at least 4 days. Therefore, for the treatment of endophthalmitis the intravitreal route of gentamicin administration is of the greatest practical importance.