METHADONE

).

Posology Adults:

In the treatment of opioid drug addiction. Initially 10-20mg per day, increasing by 10-20mg per day until there are no signs of withdrawal or intoxication. The usual dose is 40 -60mg per day. . The dose is adjusted according to the degree of dependence, with the aim of gradual reduction.

Providing a dosage schedule is difficult as it is largely subjective based on the addict’s reported drug use and a clinical assessment of their dependence. A cautious approach is usually adopted starting at a low dose and following with incremental increases as judged appropriate bearing in mind the general health of the patient.

5 below). Treatment of moderate to severe pain Usually 5-10 mg at six to eight hours although doses should be adjusted according to response. In prolonged use it should not be administered more than twice a day.

Elderly and debilitated patients :

In the case of the elderly or ill patients, repeated doses should be given with extreme caution due to the long plasma half-life. There may be a greater risk of respiratory depression, with or without any associated renal or hepatic impairment in this age group.

Paediatric population As methadone has not been studied in children, it should not be used in children under the age of 16 years until further data become available. Hepatic impairment In patients with severe liver damage, the dose of methadone should be carefully controlled as there is a risk that methadone might precipitate porto-systemic encephalopathy.

Method of Administration Sterile solution for subcutaneous or intramuscular injection. If repeated doses are required the intramuscular route should be used. The intramuscular route is preferred when repeated administration is required.

Volumes greater than 2mI (20mg) may need to be given in divided doses at different sites

Methadone is associated with undesirable effects similar to other opioid analgesics. There are no modern clinical studies available that can be used to determine the frequency of undesirable effects. Therefore, all the undesirable effects listed are classed as "frequency unknown".

4) General disorders and administration site conditions: Uncommon: drug withdrawal syndrome Nervous System Disorders: Drowsiness, dizziness, vertigo. Eye Disorders:- Dry eyes, visual disturbances such as miosis. Cardiovascular Disorders Bradycardia, tachycardia, palpitations, QT prolongation, torsades de pointes..

Vascular Disorders:

Orthostatic hypotension. 9), dry nose. Gastrointestinal Disorders Nausea and vomiting (particularly at the start of treatment), constipation, biliary spasm and dry mouth Skin and Subcutaneous tissue Disorders Sweating, facial flushing, rashes (urticaria, pruritus), oedema Musculoskeletal, Connective Tissue and Bone Disorders Muscle rigidity Renal and Urinary Disorders Micturition difficulties, urinary retention, ureteric spasm Reproductive System & Breast Disorders Decreased libido, dysmenorrhoea, amenorrhoea, sexual dysfunction General and Administration Site Disorders Hypothermia Reporting of suspected adverse reactions Reporting suspected adverse reactions after authorisation of the medicinal product is important.

It allows continued monitoring of the benefit risk balance of the medicinal product. uk/yellowcard).

In the case of elderly or ill patients, repeated doses should only be given with extreme caution. Methadone is a drug of addiction and is controlled under the Misuse of Drugs Act 1971 (Schedule 2). Methadone has a long half life and can therefore accumulate.

A single dose which will relieve symptoms may, if repeated on a daily basis, lead to accumulation and possible death. Methadone can produce drowsiness and reduce consciousness although tolerance to these effects can occur after repeated use.

Drug dependence, tolerance and potential for abuse For all patients, prolonged use of this product may lead to drug dependence (addiction), even at therapeutic doses. , major depression). Additional support and monitoring may be necessary when prescribing for patients at risk of opioid misuse.

A comprehensive patient history should be taken to document concomitant medications, including over-the-counter medicines and medicines obtained on-line, and past and present medical and psychiatric conditions. Patients may find that treatment is less effective with chronic use and express a need to increase the dose to obtain the same level of pain control as initially experienced.

Patients may also supplement their treatment with additional pain relievers. These could be signs that the patient is developing tolerance. The risks of developing tolerance should be explained to the patient. Overuse or misuse may result in overdose and/or death.

It is important that patients only use medicines that are prescribed for them at the dose they have been prescribed and do not give this medicine to anyone else. Patients should be closely monitored for signs of misuse, abuse or addiction.

The clinical need to analgesic treatment should be reviewed regularly. Drug withdrawal syndrome Prior to starting treatment with any opioids, a discussion should be held with patients to put in place a withdrawal strategy for ending treatment with methadone hydrochloride.

1 Patients with respiratory depression and obstructive airways disease. Use during an acute asthma attack. Concurrent administration with monoamine oxidase inhibitors, or within 2 weeks of discontinuation of treatment with them. Phaeochromocytoma.

Opiates may induce the release of endogenous histamine and stimulate catecholamine release Risk of paralytic ileus. Comatose patients.