Comparative review of topical ophthalmic antibacterial preparations

The choice of an antibacterial is based on considerations of pharmacodynami c, pharmacokinetic and bacteriological characteristics, risk of selecting r esistant mutants, and cost, In this article we review 16 commercially avail able ophthalmic antibacterial preparations. Fusidic acid and bacitracin are selective for Gram-positive bacteria wherea s polymyxin B targets Gram-negative species, Aminoglycosides and quinolones are broad spectrum antibacterials, The widespread use of an antibacterial increases risks of selecting resistance to it, Acquired resistance is well documented for fusidic acid and rifamycin, and newly described for quinolon es. The bioavailability of an antibacterial agent depends an the target bacteri al species, the site of infection and the integrity of the haemato-aqueous barrier,Some agents (fusidic acid, quinolones) penetrate the cornea, passin g into the anterior chamber of normal eyes at therapeutic concentrations, w hereas others (polymixin B, bacitracin) have no penetrating powers and rema in at the surface of the eye. Toxicity is mostly manifested by allergic reactions to excipients or active ingredients in topical antibacterial preparations. A few cases of haematol ogical toxicity have brought suspicion on topical chloramphenicol, but the link has yet to be proven. Erythromycin and polymyxin B are probably okay t o use as topical applications in pregnant women and nursing mothers. Costs of treatment must be evaluated as a whole (regimen, drug associations ). Prices for a bottle of eyedrops may vary S-fold. The cheapest drugs incl ude chloramphenicol, polymyxin B and gentamicin, the most expensive being f usidic acid and the quinolones.