The penetration of antistaphylococcal antibiotics into the aqueous humor of rabbits.

A multiple dose schedule of antibiotic administration parallels the clinical therapeutic situation. However, most reported studies on the aqueous humor concentration of antibiotics have been carried out following single doses of drug. We administered 2 penicillinase-resistant penicillins, 2 cephalosporins, and gentamicin to rabbits over a 24 hour period. Samples of serum and aqueous humor were obtained after the first and after the fifth dose of antibiotic. Of the agents studied, only methicillin in multiple doses gave therapeutic concentrations in the aqueous humor of normal rabbits. It is proposed that any future studies of intraocular penetration of antimicrobials be designed to include single and multiple doses in normal and infected eyes.