Vidalta^® Questions and Answers

Feeding at time of giving a Vidalta tablet can affect the bioavailability of the active ingredient Carbimazole by around 40%¹.

Therefore, if an animal’s T4 result is too high try giving the tablet with food or if the animal’s T4 result is too low try giving the tablet without food.

There is not a set time to blood sample for T4 in relation to when the Vidalta tablet is given. Providing that the following three points apply:

• The patient has received Vidalta medication consistently every day for at least ten days
• The tablet has been consistently given with or without food
• The tablet has been given consistently every 24 hours

T4 levels in the blood do not rise and fall in direct sympathy with the rise and fall of plasma methimazole. Rather the rise and fall of T4 levels in blood correlates well with the average plasma methimazole level over the course of 24 hours. This means that it should not matter when the sample is taken in relation to when the tablet was administered provided that the cat has been on the medication consistently for at least ten days.

In the clinical field trial for Vidalta, all the cats were blood sampled 6 hours post tablet administration. This was based on the fact that:

1) in a clinical trial every aspect of that trial has to be uniform so to avoid any bias

2) six hours was the point of maximal peak methimazole plasma concentrations in the pharmacokinetic studies.

This was decided to be as good a time as any to blood test. However, based on the duration of action of the product and the mechanisms of thyroid hormone storage and release, when to blood sample in relation to when the Vidalta tablet is given is not critical.

It is not recommended to crush or break Vidalta tablets.

If crushed or broken, Vidalta loses the sustained release action of the formulation and therefore loses the once a day advantage of the active ingredient Carbimazole.