Intraocular levels of cefuroxime in inflamed rabbit eyes

The pharmacokinetics of cefuroxime was studied in the inflamed rabbit eye employing subconjunctival, intravitreal and combined intravitreal-intravenous routes of administration to study the intraocular levels and the duration of minimum inhibitory concentrations (MIC) of the antibiotic in the vitreous and in the aqueous. A standard inoculum of viable S. aureus was injected into the vitreous of 36 pigmented rabbits to establish experimental endophthalmitis. A biological method was used for the antibiotic assay. Penetration of systemically and subconjunctivally administered-cefuroxime into the inflamed vitreous was poor. Intraocular inflammation increased the clearance of the intravitreally injected cefuroxime. A dose of 75 mg subconjunctivally produced levels in the aqueous far exceeding MIC for over six hours. Penetration of intravitreally injected cefuroxime into the aqueous was poor, inconsistent and short lasting. Following a single intravitreal injection of 1000 micrograms cefuroxime, levels exceeding the MIC for common ocular pathogens persisted in the vitreous for at least 24 hours but supplementation with intravenous cefuroxime neither increased the intraocular levels nor delayed the clearance of the intravitreally injected antibiotic.