Pharmacokinetics of albendazole sulfoxide enantiomers administered in racemic form and separately in rats

The pharmacokinetic behaviour of albendazole sulfoxide (ABZSO) enantiomers was studied in rats after the oral administration of 10 mg/kg of rac-ABZSO, 5 mg/kg of (−)-ABZSO or 5 mg/kg of (+)-ABZSO. The disposition profiles of ABZSO enantiomers were similar in all treatments, but the calculated area under the curve for the (−)-ABZSO was higher in all cases compared with (+)-ABZSO. The results suggest that there is no chiral inversion of ABZSO enantiomers. After the administration of rac-ABZSO, 17.2% of the total dose was recovered in urine as albendazole ABZ (0.1%), albendazole sulfone ABZSO2 (0.3%), albendazole 2-aminosulfone (ABZ-SO2NH2) (3.1%) and ABZSO (13.7%). The ratio (+) to (−) was similar in urine (1.6) and blood (1.7).