Vidalta

Thiamazole (methimazole), the active metabolite of carbimazole, inhibits thyroid hormone
production and therefore cessation of treatment with carbimazole will result in a rapid
(within 48 hours) return to pre-treatment thyroid hormone levels. Chronic administration
is therefore necessary unless surgical or radiation-induced thyroidectomy is performed.
A small proportion of cats with thyroid adenoma may fail to respond or have a poor
response to treatment.
Thyroid carcinoma is a rare cause of hyperthyroidism in the cat and medical management
alone is not recommended in such cases as it is not curative.

Special precautions for use in animals
Treatment should be adjusted according to a benefit-risk assessment by the responsible
veterinarian in each individual case.
Treatment of hyperthyroidism may result in a reduction in the glomerular filtration rate.
This can lead to unmasking of pre-existent renal dysfunction. Treatment of
hyperthyroidism may also induce an elevation of liver enzymes or a worsening of pre-
existing hepatic disorders. Renal and liver function should therefore be monitored before
and during treatment
Due to risk of leucopaenia or haemolytic anaemia, haematology parameters should be
monitored on a regular basis before and during treatment, preferably at each visit of the
dose adjustment phase and maintenance phase (see section 4.9).
Any animal that suddenly appears unwell during therapy, particularly if they are febrile,
should have a blood sample taken for routine haematology and biochemistry.
Neutropaenic animals (neutrophil counts <2.5 x 10
/L) should be treated prophylactically
with bactericidal antibiotics and supportive therapy.
Doses above 20 mg have only been trialled in a small number of cats and should be used
with caution.
Therefore, careful monitoring is recommended and the dose should be adjusted in
individual cases following a benefit-risk assessment by the responsible veterinarian.

Revised: December 2024
AN: 02169/2024
Special precautions to be taken by the person administering the veterinary medicinal
product to animals
People with a known hypersensitivity (allergy) to carbimazole or any of the excipients
should avoid contact with the product.
If allergic symptoms develop, such as a skin rash, swelling of the face, lips or eyes or
difficulty in breathing, you should seek medical attention immediately and show the
package leaflet or label to the physician.
Carbimazole, as a prodrug of thiamazole (methimazole), may cause vomiting, epigastric
distress, headache, fever, arthralgia, pruritus and pancytopenia.
Avoid dermal contact and oral exposure, including hand-to-mouth contact.
Do not break or crush tablets.
Do not eat, drink or smoke while handling the tablet or used litter.
Wash hands with soap and water after administration of the product and when handling
litter used by treated animals.
In the case of accidental ingestion, seek medical advice immediately and show the
package or the label to the physician.
Carbimazole is a suspected human teratogen.
Women of child-bearing age must wear non-permeable, single use gloves when
administering the product or handling litter/vomit of treated cats. If you are
pregnant, think you may be pregnant or are attempting to conceive, you should not
administer the product or handle the litter/vomit of treated cats.