Ocular penetration kinetics of fosfomycin administered as a one-hour infusion

The penetration of fosfomycin in aqueous humour was studied in 21 patients who were to undergo cataract surgery. All patients received 4 grams of fosfomycin as an infusion lasting one hour. Concentrations of the drug in aqueous humour were measured 1, 2, 4, 6 and 12 hours after the start of infusion. Drug concentrations in aqueous humour and serum were measured by HPCE (High Performance Capillary Electrophoresis). The aqueous humour concentration at one hour was 11.46 mg/l +/- 2.12. Peak concentration was 14.63 mg/l +/- 5.54, reached two hours after the infusion. Concentrations were high until 6 hours and remained significant at 12 hours. These results confirm the excellent diffusion of fosfomycin in aqueous humour, with high levels at 12 hours. They justify its use in intraocular infections, by infusions repeated every eight hours, to maintain concentrations above the MIC 90 for organisms usually susceptible to the drug.