Ricobendazole kinetics and availability following subcutaneous administration of a novel injectable formulation to calves

• Published in: Research in veterinary science 1998-07, Vol.65 (1), p.5-10
• Main Authors: Lanusse, C.E., Virkel, G.L., Sanchez, S.F., Alvarez, L.I., Lifschitz, A.L., Imperiale, F., Monfrinotti, A.
• Format: Article
• Language: English
• Subjects: Administration, Oral; Albendazole - administration & dosage; Albendazole - analogs & derivatives; Albendazole - metabolism; Albendazole - pharmacokinetics; Animals; Anthelmintics - administration & dosage; Anthelmintics - metabolism; Anthelmintics - pharmacokinetics; Area Under Curve; Biological Availability; Cattle - blood; Cattle - metabolism; Chromatography, High Pressure Liquid; Half-Life; Injections, Subcutaneous
• ISSN: 0034-5288; 1532-2661
• DOI: 10.1016/S0034-5288(98)90019-4

The plasma and abomasal fluid disposition kinetics of ricobendazole (RBZ) after subcutaneous (SC) administration of novel injectable formulation to calves, and the comparative plasma availability after SC injection of RBZ and that obtained after oral treatment with albendazole (ABZ), were characterised. Six parasite-free Holstein calves received RBZ (solution 150 mg ml −1) by SC injection at 3·75 mg kg −1 (Experiment 1). Experiment 2 was conducted in two experimental phase; in phase I, five calves (Group A) received RBZ by SC injection and five animals (Group B) were orally treated with ABZ (suspension 100 mg ml −1, at 5 mg kg −1. Drug treatments were reversed for each group in phase II and given at 7·5 mg kg −1. Samples of abomasal fluid via cannula) and jugular blood were collected over 72 hours post-treatment and analysed by HPLC. RBZ and it, sulphone metabolite were detected in plasma following its Sc administration. RBZ was rapidly absorbed, reaching the plasma C max at 4·5 hours post-dosing. The sulphone metabolite followed a similar kinetic pattern. Both molecules were rapidly and extensively distributed into the abomasum, being detected in abomasal fluid between 30 minutes and 36 hours post-administration. An extensive plasma/abomasum exchange process, with ionic-trapping in the abomasum. accounted for the higher AUC value (>200 per cent obtained for RBZ in abomasum compared with plasma. The SC treatment with RBZ formulated as a Solution resulted in a significantly greater plasma availability (measured as ABZ sulphoxide) than the oral treatment with ABZ (suspension) given at the same dose rates.