Studies on the excretion of robenidine hydrochloride in rabbit urine and feces

Objective In order to investigate the excretion quantitation of robenidine in rabbit urine and feces, a high performance liquid chromatography (HPLC) method was developed to detect the concentrations of robenidine hydrochloride.

Method Twelve healthy rabbits were administered robenidine hydrochloride orally with a dose of 15 mg·kg^-1.After administration, all of their urine and feces were collected at different time intervals and mass were achieved.Feces 0.2 g was extracted using chloroform-methanol V(chloroform): V(methanol) = 2: 1; urine 1 mL was extracted with φ = 0.2% acidified ethyl acetate, and the organic phase was separated and evaporated.The residue was redissolved with acetonitrilewater V(acetonitrile) : V(water) = 30 : 70 solution, and cleaned up by solid-phase extraction using CNW HLB after being evaporated to dryness; the residue was redissolved in methanol, and then analyzed by HPLC.

Result and conclusion The results showed that the limit of detection (LOD) and the limit of quantitation (LOQ) of robenidine in urine were 0.005 and 0.01 μg·mL^-1 respectively, with the proportion of the total administered robenidine being 0.56%; the LOD and the LOQ of robenidine in feces were 0.01 and 0.05 μg·g^-1 respectively, with the proportion of the total administered robenidine being 87.17%.The excretion peak time of robenidine in urine and feces was 0-6 and 6-12 h respectively, and the total amount of accumulated excretion was 28.37% and 38.46% respectively after administration.The results indicate that this method can be used to detect the concentration of robenidine in rabbit urine and feces, and most of the administered drug is excreted in the original form of urine and feces.