Pharmacokinetics of the neuroprotective glutamate antagonist NBQX (6-nitro-7-sulfamoyl-benzo(f)quinoxaline-2,3-dione) in mice, rats, and dogs. Interactions with probenecid

Abstract

NBQX [6-nitro-7-sulfamoyl-benzo(f)quinoxaline-2,3-dione] has proven effective in protecting against cerebral ischemic insult in rodents. The preclinical development included pharmacokinetic and toxicological investigations in mice, rats, and dogs. For these purposes, NBQX was given as an intravenous bolus dose (in mice, rats, and dogs) or as a constant infusion for up to 4 weeks in rats and dogs. In NMRI mice t1/2, CL, and V2 were 1-4 hr, 0.6-1 liter/kg/hr, and 1-4 liters/kg following 3, 10, or 30 mg/kg. In Wistar and Sprague-Dawley rats, the mean +/- SD values of t1/2, CL, and Vz were 0.8 +/- 0.35 hr, 3.2 +/- 1.0 liters/kg/hr, and 4.0 +/- 1.1 liters/kg, respectively. About 33 +/- 5.2% of the dose was excreted unchanged in urine. The CLR was 0.90 +/- 0.20 liter/kg/hr. The pH of the urine samples ranged from pH 6.2 to 8.8, with a mean of 7.9 +/- 0.72. The plasma concentrations were proportional to the dose rate in the dose range 0.3-10 mg/kg/hr, independent of sex, and did not change during 4 weeks of infusion. CL and CLR were decreased to half their value when NBQX was administered in combination with probenecid. In beagle dogs, t1/2 and Vz were 1-3 hr and 1-3 liters/kg, respectively. The CL was determined to be 1.5 +/- 0.4 liters/kg/hr (N = 18) following 2 days of infusion (0.2-1 mg/kg/hr), but after 1 month CL had decreased significantly (p < 0.0001) to 1.0 +/- 0.1 liter/kg/hr.(ABSTRACT TRUNCATED AT 250 WORDS)