Pharmacokinetics of controlled-release carbimazole tablets support once daily dosing in cats

J Vet Pharmacol Ther. 2008 Jun;31(3):213-9. doi: 10.1111/j.1365-2885.2008.00949.x.


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 (Vidalta), 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 (t(max) 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Administration, Oral
  • Animals
  • Antithyroid Agents / blood
  • Antithyroid Agents / metabolism
  • Antithyroid Agents / pharmacokinetics*
  • Area Under Curve
  • Biological Availability
  • Carbimazole / metabolism
  • Carbimazole / pharmacokinetics*
  • Cats
  • Chemistry, Pharmaceutical
  • Delayed-Action Preparations
  • Fasting / metabolism
  • Female
  • Male
  • Methimazole / blood*
  • Methimazole / metabolism
  • Methimazole / pharmacokinetics


  • Antithyroid Agents
  • Delayed-Action Preparations
  • Methimazole
  • Carbimazole