Cefoxitin levels in human aqueous humor

We administered 2 g of cefoxitin to 25 patients before cataract surgery. An additional 23 patients received 500 mg of probenecid 30 minutes before the 2-g doses of cefoxitin. Average aqueous humor levels of 1.54, 3.16, 2.46, 1.22, and 0.82 microgram/ml were achieved at 30 minutes and one, two, four, and six hours, respectively, after the 2-g dose. The addition of probenecid prolonged significant aqueous humor levels. Therapeutic levels against common gram-positive pathogens were consistently achieved at two hours after injection without probenecid and from two to four hours after injection with probenecid. Therapeutic levels effective against Enterobacteriaceae were inconsistent.