Ocular penetration of topical chloramphenicol in humans

Commercial ophthalmic chloramphenicol solutions and ointments were applied to human eyes, and the concentrations of chloramphenicol in aqueous humor and tear samples were analyzed using gas-liquid chromatography. Within several minutes after a single application of 0.5% chloramphenicol solution, the tear concentrations of the drug had fallen below 1 mg/liter, the minimal bacteriostatic concentration for many ocular pathogens. Repeated drops of 0.5% chloramphenicol solutions during several hours were required to produce an aqueous humor concentration of 1 mg/liter. A single application of 1% chloramphenicol ointment gave prolonged drug concentrations in the tears and aqueous humor, falling to 1 mg/liter in two to four hours. The repeated use of chloramphenicol solution or ointment was well tolerated by the patients. We conclude that the penetration of chloramphenicol in the anterior segment of the eye is best carried out by the repeated application of chloramphenicol ointment.