Pharmacokinetics and tissue residues of albendazole sulphoxide and its metabolites in donkey after intramuscular injection

Background Various anti‐parasitic drugs are used to control donkey parasitic diseases. The abuse of donkey drugs leads to the disposition of residues in the edible parts of treated donkeys. Objectives The aim of this study was to (1) analyse the pharmacokinetics of ABZSO to serve as reference for the dosage regimen in donkey; and (2) calculate the withdrawal times of the ABZSO in the tissue of the donkey. Methods The concentrations of ABZSO and its metabolites in plasma and tissues were determined using high‐performance liquid chromatography with an ultraviolet detector. Pharmacokinetic analysis was performed by the programme 3p97. Results The plasma concentrations of ABZSO and ABZSO 2 concentration–time data in donkey conformed to the absorption one‐compartment open model. The of ABZSO was 0.67 h, whereas the t 1/2 k e was 12.93 h; the C max and the T p were calculated as 0.58 μg mL −1 and 3.01 h. The V d/F of ABZSO was estimated to be 10.92 L kg −1 ; the area under the curve (AUC) was 12.81 μg mL −1 h. The C max and AUC values of ABZSO were higher than those of ABZSO 2 ; however, t 1/2 K e and V d/F were lower. Other pharmacokinetics parameters were similar between the two metabolites. Conclusions The results revealed that ABZSO 2 was the main metabolite of ABZSO in donkey plasma. The concentrations of ABZSO and its chief metabolite (ABZSO 2 ) were detected in liver, kidney, skin and muscle; however, ABZ‐SO 2 NH 2 was only detected in liver and kidney. The results also revealed that the depletion of ABZSO and its metabolite in donkey was longer, especially in skin.