Pharmacokinetic Assessment of Novel Controlled Release Formulations of Ricobendazole Intended for Oral Administration in Dogs

Abstract

The aim of this study was to evaluate the influence of different matrices developers on the pharmacokinetic behavior of Ricobendazole (RBZ) controlled release (CR) formulations and test their correlation in vitro-in vivo, using one Albendazole (ABZ)-based and one RBZ-based immediate-release formulation as references. The main excipients used for CR formulations were Hydroxypropyl Methyl Cellulose, Cetyl Alcohol, Gelucire 50/02® and Alginic Acid. Pharmacotechnical quality control tests were successfully completed. Twelve parasite-free no pregnant dogs were randomly divided into six groups and received different treatments (single oral doses) using an incomplete block design (two phases) (n=4). Phase I: treatment "A" (ABZ-based immediate-release formulation [25 mg/kg]). Treatment "B" (RBZ-based immediate release formulation [20 mg/kg]) and treatments from "C" to "F" (CR formulations [20 mg/kg]). Phase II was performed after 21 days of washout period. Blood samples were collected over 48 h and analysed by UV High Performance Liquid Chromatography. In vitro dissolution profiles showed that matrices agents favored a reservoir effect. Active metabolite Albendazole sulphoxide (ABZSO) or Ricobendazole (RBZ) plasma exposure measured in terms of area under concentration vs time curve (AUC) of all RBZ formulations was greater (p<0,05) when compared with that obtained for ABZ reference formulation. No statistical differences in AUC values were found among all RBZ formulations assayed (p>0.05). Nevertheless, RBZ-Cetyl alcohol formulation showed a statistical difference on its time peak concentration (p<0.05). In conclusion the results obtained in vitro do not correlate with those obtained in vivo, being this work useful to identify other matrices developers in RBZ-CR formulations.