DVM-MS Student UTKCVM Knoxville, TN, United States
Abstract: Background – Anthelmintic resistance is a worldwide problem, and few products are FDA-approved for use in goats. Pharmacokinetic data is sparse for levamisole in goats despite it being an efficacious anthelmintic. Hypothesis/Objectives – The purpose of this study was to generate the levamisole pharmacokinetic parameters from a levamisole–doramectin combination when given subcutaneously to goats. A secondary objective was to gather pilot pharmacodynamic data for this product. Animals – Six healthy goats from a university teaching herd were used. Methods – An injectable levamisole formulation was administered subcutaneously to six goats. Blood samples were drawn at 14 time points. This process was repeated using a commercially available oral drench after a 14-day washout period. The drug present in the samples was quantified using high performance liquid chromatography. Standard pharmacokinetic parameters were generated. Fecal egg count reduction testing was performed pre- and post- treatment with the injectable product. Results – After one subcutaneous injection, the average maximum plasma concentration (Cmax) was 468.57 ng/mL, time to Cmax (Tmax) was 2.24 hours, area under the curve (AUC) was 3206.42 h*ng/mL, and elimination half-life (T1/2) was 2.36 hours. The relative bioavailability of the subcutaneous formulation as compared to the oral formulation was 185%. No adverse effects were observed. Reduction in fecal egg count was observed. Conclusions and Clinical Importance – The tested levamisole product represents a possible choice as an anthelmintic in goats. Further field trials are needed, but the preliminary data outlined in this study is suggestive of the product’s efficacy and safety.
