S A Haider.
Intraocular level of Antibiotics in Bacterial Endophthalmitis and the timing of repeat injection.
Pak J Ophthalmol Jan ;14(1):28-33.

Purpose: To determine the antibiotic levels attained in aqueous and vitreous following intravitreal therapy for endophthalmitis and assess the timing and dose for reinjection. Method: Antibiotic levels were measured by fluorescence polarization immunoassay in eleven patients following intravitreal injection of 2mg of vanomycin in ten patients and 1mg in one patient. Results: 24 to 72 hours after intravitreal injection of vancomycin 1-2mg, aqueous levels ranged from 8.4 to 170mg/L and vitreous levels were 38.65-220mg/L. Conclusion: Aqueous and vitreous vancomycin levels were well within the therapeutic range, sometimes at retinotoxic level. Since the earliest sample was at 24 hours, it is likely that `retinotoxic` levels are reached using standard dosing. In all cases suprathreshold level of vancomycin was available in the vitreous at the time of assay. 1, therefore, feel that the injection should be repeated, if necessary, 72 hours after the first injection and at a lower dose than 2mg.

PakMediNet -Pakistan's largest Database of Pakistani Medical Journals - http://www.pakmedinet.com