Methadone : 

•  Properties : Central nervous system depressant, narcotic analgesic.

This long-term treatment has proved to be efficient in order to reduce illicit consumption of opiates and drug-related crime, and to allow for rehabilitation in the community. Methadone available as a soluble powder to be taken orally is a synthetic opioid which is mainly distinguished from morphine (natural opiate) and heroin (semi synthetic opiate) by its long-acting effects.

It has an agonist effect on the nervous system's receptors, which gives it similar properties to morphine. Its analgesic properties can be compared favourably to those of the morphine. Its main effects are felt within 2 to 4 hours following ingestion. The half-life of methadone is quite long and one single dose taken by a stabilised patient could linger for 24 to 36 hours, letting him/her function normally without experiencing withdrawal or feeling sleepy. If the morphine receptors are occupied, the effect of the heroin will be reduced or annulled if the patient uses any. This is known as crossed tolerance phenomenon to other opiates, so that methadone can block the exhilarating effect of heroin. Serum stability can only be reached after five days of continuous administration of the substance. Three to five days are necessary to make sure the prescribed dose is effective.  

•  Short-term effects : Unlike heroin, which gives intense sensations to users, methadone provokes a slight euphoria, indifference and withdrawal. It also is a cough suppressant. When the dosage is right, it should prevent physical withdrawal syndrome usually associated with heroin deprivation, and prevent the craving for drug use. It reduces the effects of heroin used concurrently with methadone, thereby reducing the bigger problem represented by the concurrent consumption of other psychoactive substances during the treatment with methadone. Like for other opiates, the main side effects are constipation, weight gain, peripheral oedema, pruritus, drowsiness (overdose), sweating, gynaecomasty, loss of sex drive, sexual dysfunction, etc.

•  Overdosing : Overdosing on methadone can cause respiratory arrest. Methadone is not compatible with alcohol, tranquillisers, sleeping tablets and analgesics. Its use on top of any of those drugs could have harmful effects and be life threatening. 

•  Long term effects : With the appropriate dosage, methadone is reasonably tolerated, as reported by cases of prolonged use for over 15 years without harmful effects .