Comfortan 10 mg/ml, Solution for Injection for Dogs and Cats

Due to the variable individual response to methadone, animals should be monitored
regularly to ensure sufficient efficacy for the desired duration of effect.
Use of the veterinary medicinal product must be preceded by a thorough clinical
examination.
In cats, pupil dilation is seen long after the analgesic effect has disappeared. It is therefore
not an adequate parameter to assess clinical efficacy of the administered dose.
Greyhounds may require higher doses than other breeds to achieve efficacious plasma
levels.

i). Special precautions for use in animals
Methadone may occasionally cause respiratory depression and, as with other opioid
drugs, care should be taken when treating animals with impaired respiratory function, or
animals that are receiving drugs that can cause respiratory depression. To ensure safe
use of the veterinary medicinal product, treated animals should be monitored regularly,
including examination of heart rate and respiratory rate.
As methadone is metabolised by the liver, its intensity and duration of action may be
affected in animals with impaired liver function.
In cases of renal, cardiac or hepatic dysfunction, or shock, there may be greater risk
associated with the use of the veterinary medicinal product.
The safety of methadone has not been demonstrated in dogs less than 8 weeks and cats
less than 5 months of age.
The effect of an opioid on head injury is dependent on the type and severity of the injury
and the respiratory support supplied.
Safety has not been fully evaluated in clinically compromised cats.
Due to the risk of excitation, repeated administration in cats should be used with care.
The benefit/risk ratio for using the veterinary medicinal product should be made by the
attending veterinarian.
ii). Special precautions to be taken by the person administering the veterinary medicinal
product to animals
Methadone can cause respiratory depression following spillage onto the skin or accidental
self-injection. Avoid skin, eye and mouth contact, and wear impermeable gloves when
handling the veterinary medicinal product. In cases of spillage onto the skin, or splashing
into the eyes, wash immediately with large amounts of water. Remove contaminated
clothes.
People with known hypersensitivity to methadone should avoid contact with the veterinary
medicinal product. Methadone has the potential to cause stillbirths. The veterinary
medicinal product should not be administered by pregnant women.
In case of accidental self-injection, seek medical advice immediately and show the
package leaflet or label to the physician but DO NOT DRIVE as sedation may occur.

Revised: November 2023
AN: 03056/2022
To the physician: Methadone is an opioid whose toxicity may cause clinical effects
including respiratory depression or apnoea, sedation, hypotension and coma. When
respiratory depression occurs controlled ventilation should be installed. Administration of
the opioid antagonist naloxone to reverse the symptoms is recommended.
Special precautions for the protection of the environment:
Not applicable.
iii). Other precautions
Not applicable.