Pharmacokinetics of Controlled-Release Carbimazole Tablets Support Once Daily Dosing in Cats

R. Frenais, S. Burgaud and L. J. I. Horspool

Journal of Veterinary Pharmacology and Therapeutics, 2008. 31(3): p.213-219.


FrÈnais, R., Burgaud, S., Horspool, L. J. I. Pharmacokinetics of controlled-release carbimazole tablets support once daily dosing in cats. J. Vet. Pharmacol. Therap.31, 2132013219. Carbimazole, a prodrug of methimazole, is used in the treatment of hyperthyroidism in cats. The pharmacokinetics of methimazole was investigated in healthy cats following oral administration of 15†mg of carbimazole as a controlled-release tablet (VidaltaÆ, Intervet). The controlled-release tablet did not produce a pronounced concentration peak and methimazole was present in the circulation for a sustained period, compared with a conventional tablet formulation. The time to reach peak concentrations after carbimazole administration was quite long (tmax 6†h). The absolute bioavailability of carbimazole was around 88†±†11%. Repeated oral administration daily for 13 consecutive days did not lead to accumulation of methimazole in plasma. The extent of absorption of carbimazole was about 40% higher when administered to cats that had been fed compared to fasted cats. The relative oral bioavailability of methimazole following administration of the controlled-release tablets was similar to that of a conventional release formulation (83†±†21%). The pharmacokinetics of this controlled-release formulation of carbimazole supports its use as a once daily treatment (both as a starting dose and for maintenance therapy) for cats with hyperthyroidism.