Methone Injection 20ml

COMPOSITION
Methadone hydrochloride 10 mg/mL.

ACTIONS
Provides analgesia that peaks between 10 and 20 minutes after administration and persists for three to five hours. Methadone is a potent morphine analogue neuroleptanalgesic which raises the pain threshold by binding to μ-opiate receptors. It is pharmacologically similar to, but has approximately three times the analgesic potency of, morphine. The narcotic action of methadone is antagonised by naloxone.

Pharmacokinetics Methadone is detectable in the plasma within 10 minutes after subcutaneous injection. Firm protein binding appears to occur in various tissues, including the brain. Methadone undergoes extensive biotransformation in the liver and the metabolites are predominantly excreted in the bile and urine, together with small amounts of unchanged drug.

INDICATIONS
Analgesia and restraint in horses; and analgesia and anaesthetic premedication in dogs.
Horses: Methone Injection is an effective agent of restraint and analgesia in horses, when used in combination with acetylpromazine, facilitating treatment of wounds, handling and loading of difficult animals, suturing, laryngoscopy, castration and minor surgical procedures. Following intravenous administration, the onset of action is rapid and clinical effect is usually sufficient within three minutes to begin the procedure. Horses rarely become recumbent or ataxic after methadone and acetylpromazine administration, even at high doses. Clinical doses produce a somnolent but aware state in which the patient is tractable, placid and sufficiently coordinated to minimise risk of injury to the animal or operator.
Methone Injection may be used as a premedicant to xylazine sedation or barbiturate or ketamine anaesthesia to provide effective analgesia and restraint during painful procedures.

Dogs: Methone Injection may be used in premedication of barbiturate anaesthesia. Barbiturates have extremely poor analgesic properties, even at high dose rates. Methadone premedication of barbiturate anaesthesia smooths induction and greatly minimises the risk of drug toxicity by enabling the dose of barbiturate to be halved.

PRESENTATION
20 mL sterile multidose vial

STORAGE
Store below 30°C (room temperature). Protect from light. To avoid microbial contamination, use the contents of the vial within 24 hours of initial broaching and discard any unused portion.

CONTRAINDICATIONS
Do not use in animals during parturition. Do not administer to animals with respiratory depression. Do not administer to cats. Do not use in horses intended for human consumption.

PRECAUTIONS
Use with caution in animals with hypothyroidism, adrenocortical insufficiency, impaired renal and hepatic function and shock.
Withholding Periods Meat Do not use in horses intended for human consumption.