ANIMAL PHARMACOKINETICS OF FK037, A NOVEL PARENTERAL BROAD-SPECTRUM CEPHALOSPORIN

Single-dose pharmacokinetics of FK037 has been investigated in laboratory animals. After bolus intravenous dosing with 20 mg/kg, the elimination half-life of FK037 varied in the species; with values of 0.27, 0.30, 0.97, 1.29 and 1.76 hours in mice, rats, rabbits, dogs and monkeys, respectively. The volume of distribution ranged between 260 ml/kg in rats and 390 ml/kg in dogs. These parameters approximated those of ceftazidime and cefpirome used as reference drugs. The renal clearance of FK037 was almost equal to-glomerular filtration rate (GFR) in rabbits. Probenecid did not affect the elimination half-life of FK037 and its clearance ratio to GFR. These findings suggest that FK037 is solely excreted by glomerular filtration. FK037 readily penetrated into the tissues and inflammatory exudate fluid in rats, and the tissue level was highest in the kidneys, and decreased in the following order; lungs > heart > liver > spleen. Penetration of FK037, cefpirome and ceftazidime into the cerebrospinal fluid were determined using induced staphylococcal meningitis in rabbits. The penetration percentage ranged from 14.2 to 16.0% for these drugs with no significant differences. The major route of excretion of FK037 was via the kidney, with more than 74% of the dose being excreted in the urine within 24 hours after dosing to each species. Biliary excretion was low, 0.79% in rats. Bioautograms showed only unchanged drug in the plasma, urine and bile. Serum protein binding was low (8.8 to 17.6%) in all the species studied.