Bioavailability of antibiotics

To be effective, an antibiotic must achieve therapeutic concentrations at t he site of infection. This article is a review on the bioavailability of lo cal and systemic antibiotics. Amongst topical antibiotics, fluoroquinolones and fusidic acid have the bes t intra-corneal and intra-cameral penetration. Chloramphenicol penetrates t he anterior chamber but not always at therapeutic levels. Serum levels are low from topical administration, and haematological toxicity of chloramphen icol eyedrops is still not proven. Amongst systemic antibiotics, the molecules capable of penetrating the eye at therapeutic levels are fosfomycin, imipenem, some of third generation ce phalosporins, fluoroquinolones and ureidopenicillins. Intra-ocular penetration of antibiotics is increased by infection, corneal epithelium abrasion, increasing dose frequency or delivery using a biomater ial reservoir (soft contact lenses or collagen schields). Antibiotic-antiin flammatory associations can make infected sites more accessible to antibiot ics. The choice of a treatment must take in consideration molecules, dosing and route, and be adapted to the germ to kill and the infected site to treat.