Oral pharmacokinetics of fenbendazole in llamas, South American Camelids

Liamas, South American Camelids are increasingly popular in the United Stat es, as a source of fiber, livestock guard, and pack animals. Gastrointestin al parasites have been identified as a major health problem in all classes of livestock including Ilamas. Currently, there are no approved anthelminti cs available for use in Ilamas. In this study, the pharmacokinetics of a si ngle, oral administration of fenbendazole paste at a minimum target dose of 5 mg/kg, with an upper limit of <10 mg/kg, was evaluated in Ilamas. Plasma fenbendazole concentration time profiles were best described by a single c ompartment model. After oral administration of fenbendazole, T-max and Cp-m ax were 28.39+/-12.80 h, and 0.2+/-0.17 mu g/ml, respectively. The T-1/2 al pha, and T-1/2 beta were 16.25+/-11.67 and 36.00+/-25.00 h, respectively. T he apparent volume of distribution (V-d) and the area under the curve (AUC) were 11.28+/-4.66 l/kg, and 22.52+/-8.67 mu g h/ml, respectively. The resu lts of this preliminary study indicate that when the paste formulation of f enbendazole is administered orally to Ilamas, its rate of absorption appear s to be very similar to that of other ruminants including sheep, goats, and cattle as indicated by the time required to reach peak plasma concentratio ns. It was also found that the rate of elimination of fenbendazole was prol onged in Ilamas as compared to sheep, goats, and cattle, (C) 2000 Elsevier Science B.V. All rights reserved.