Pharmacokinetics of fenbendazole in dogs

Abstract

Fenbendazole was administered to dogs at a dose rate of 20 mg/kg body weight on a single occasion in gelatin capsules, on 5 consecutive days in feed, and on a single occasion as an alginate suspension. It was also administered at a dose rate of 100 mg/kg body weight on a single occasion in feed. Following single administration of 20 mg/kg fenbendazole mean maximum concentrations (Cmax) of the parent drug and its known active sulphoxide metabolite were 0.42 +/- 0.05 and 0.31 +/- 0.05 microgram/ml, respectively. Mean times until maximum concentrations were achieved (tmax) were 12.67 +/- 4.18 and 15.33 +/- 2.81 h, respectively, and areas under the plasma concentration-time curves (AUC) were 5.83 +/- 0.65 and 4.60 +/- 0.57 microgram.h/ml, respectively. Administration in feed increased the apparent bioavailability and administration for 5 consecutive days provided sustained plasma concentrations, generally greater than 0.2 microgram/ml. Administration as an alginate did not increase bioavailability or extend the persistence in plasma. It did increase the tmax to 16.80 +/- 2.93 and 20.00 +/- 2.53 h for fenbendazole and its sulphoxide metabolite, respectively. Increasing the dose from 20 mg/kg to 100 mg/kg did not substantially increase the Cmax or AUC.

Hyperfibrinolysis and Hypofibrinogenemia Diagnosed With Rotational Thromboelastometry in Dogs Naturally Infected With Angiostrongylus vasorum

“…All dogs were treated with fenbendazole or moxidectin and prednisolone and additional symptomatic medications as deemed necessary by the clinician in charge; 1 dog treated with fenbendazole (50 mg/kg) 6 hours before ROTEM analysis was included in the study because fenbendazole is not expected to have a clinically relevant anthelmintic effect within 6 h …”

Cystic echinococcosis therapy: Albendazole-loaded lipid nanocapsules enhance the oral bioavailability and efficacy in experimentally infected mice

“…As we mentioned above, ABZ is barely absorbed from the gastrointestinal tract since it is a poorly watersoluble drug. It was demonstrated that for monogastric species, an increment in the dose is not correlated to an increment in the AUC (McKellar et al, 1990). Moreover we demonstrated that concentrations of ABZ as low as 0.5 mg/kg exert a deleterious effect on hydatid cysts on the murine model of cystic echinococcosis (Ceballos et al, 2008).…”

Pharmacological approaches towards rationalizing the use of endoparasitic drugs in small animals

“…This observation could explain the lack of efficacy of MBZ against lung parasites in humans and dogs. The pharmacokinetics of FBZ parent drug and its metabolites in dogs were characterized by McKellar et al. (1990, 1993, who detected FBZ, its active sulphoxide (OFZ) and inactive sulphone (FBZSO 2 ) metabolites in plasma for 48 h after administration of a single oral dose of 20 mg/kg (Fig.…”

“…This results in exposure of the parasites to the FBZ moiety which has greater potency than OFZ, and thus activity against the tissue arrested larvae and other immature parasite stages (Fig. 4; McKellar et al. , 1990).…”