The Pharmacokinetics of Butylscopolamine in Camel Plasma after Intravenous Administration

Camels are commonly administered butylscopolamine (BSA), an antimuscarinic quaternary ammonium derivative, to reduce spasms in the smooth muscles of their urinary and gastrointestinal tracts. However, its presence in body fluids after racing is prohibited by animal racing authorities. The current study aimed to conduct a pilot pharmacokinetic study of BSA in healthy camels. The goal was to obtain initial pharmacokinetic parameters and use these parameters to predict plasma concentrations from the dose and clearance. This will help advise on a withdrawal time for BSA administration before camel racing. The pharmacokinetics of BSA were evaluated in three healthy camels after a single intravenous dose of 0.2 mg/kg body weight. Sensitive liquid chromatography with tandem mass spectrometry was used for the quantification of BSA and the internal standard, ipratropium, in plasma. BSA concentration versus time data were best described by a two-compartment open model. The pharmacokinetic parameters (median and range) were as follows: terminal elimination half-life was 2.29 (1.48–2.46) h, plasma clearance was 1,018.5 (772.4–1,024.0) mL/h/kg, volume of distribution at steady state was 931.9 (700.0–1,068.7) mL/kg, Cmax was 443.9 (351.1–443.9) ng/mL, and Tmax was 0.5 (0.25–0.75) h. BSA’s irrelevant plasma concentration was estimated to be 20 ng/mL. Consequently, it can be concluded that plasma would not contain BSA at the screening level of 20 ng/mL at the usual dose of 0.2 mg/kg body weight 24 h before camel racing.