We determined the ocular kinetics of pefloxacin, a new fluoroquinolone, when administered by the intramuscular route to albino and pigmented rabbits. In serum of albino rabbits, the area under the concentration-time curve (AUC) for the experimental period was 31.4 ± 1.07 ,ug. h/ml (mean ± standard deviation); the AUCs in the aqueous and vitreous humors were high (10.5 ± 1.90 and 12.4 ± 3.79 ,ug h/ml, respectively). Pefloxacin was found in the avascular ocular tissues (30.15 ± 3.79 ,ug-h/ml in the cornea and 6.98 ± 1.06 ,ug * h/ml in the lens). In the vascularized tissues, the penetration ratio, defined as tissue AUC/serum AUC, was more than 1. The good intraocular diffusion of pefloxacin might be related to its low molecular weight and to its strong lipophilicity and could explain its clinical efficacy in the treatment of endophthalmitis. In pigmented rabbits, pefloxacin levels were high in the iris (1525 ± 328 ,g. h/ml, versus 40.2 ± 5.08 ,Ag. h/ml in albino rabbits) and chorioretina (2600 ± 422 ,ug h/ml, versus 48.3 ± 7.52 ,ug. h/ml in albino rabbits), suggesting that it binds to the pigmentary apparatus. Eye infections are rare but generally serious, often leading to the loss of vision since numerous ocular tissues consist of thin membranes which are rapidly destroyed by microorganisms.When administered systemically, most antibiotics show poor ocular penetration, especially in the vitreous humor, since they must cross the blood-ocular barriers to reach the aqueous humor and retina before diffusing passively into the vitreous humor (8).Pefloxacin [1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7-(4-methyl-1-piperazinyl)-quinoline-3 carboxylic acid] is a new fluoroquinolone. It has been shown to have exceptionally good diffusion in tissues (10). After systemic administration, it has been found in the aqueous humor and lenses of patients undergoing cataract extraction (6, 9, 13).The purpose of this study was to assess the kinetics of pefloxacin in the different structures of the rabbit eye when administered by the intramuscular route. Albino and pigmented rabbits were used to determine the role of the pigmentary apparatus.MATERIALS AND METHODS Pharmacokinetic studies. Twenty-eight rabbits, each weighing approximately 2.5 kg, were used.Fourteen albino rabbits (New Zealand White) and 14 pigmented rabbits (Fauve de Bourgogne) were given a single intramuscular injection of 50 mg of pefloxacin (Roger-Bellon Laboratories, Paris, France) per kg of body weight.Blood samples were obtained prior to sacrifice by femoral artery puncture. The animals were killed with sodium pentobarbital 1, 2, 3, 5, 7, 9, or 11 h after antibiotic administration.Aqueous and vitreous samples were aspirated by puncture with a 23-gauge needle mounted on a tuberculin syringe. The eyes were removed and cleaned of conjunctival tissue and blood to avoid contamination by blood. They were immedi-* Corresponding author.ately stored at -80°C in order to minimize diffusion of the antibiotic (1).Assay. Pefloxacin (mesylate dihydrate), norfloxacin (4803 P), and intern...
