Methadyne 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 product must be preceded by a thorough clinical examination.

Revised: December 2025
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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.

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 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 case of renal, cardiac or hepatic dysfunction, or shock, there may be greater risk
associated with the use of the 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 product should be made by the attending
veterinarian.
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 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.
Pregnant women are advised not to handle the product.
In the case of accidental self-injection, seek medical advice immediately and show
the package leaflet to the physician but DO NOT DRIVE as sedation may occur.
ADVICE TO DOCTORS: 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.
Other precautions
None

Revised: December 2025
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