Metadoni

Metadoni, known in English as methadone, is a synthetic opioid used primarily in the treatment of opioid use disorder and, in some settings, for chronic pain management. It is a long-acting mu-opioid receptor agonist. When taken orally, methadone is well absorbed and its effects can last many hours, allowing often once-daily dosing in substitution programs. It is metabolized in the liver, mainly by cytochrome P450 enzymes, and can interact with other medicines and substances.

In opioid use disorder, methadone is employed as substitution therapy to suppress withdrawal symptoms and cravings, reduce illicit opioid use, and lower overdose mortality. It is typically provided as a liquid, tablet, or disintegrating tablet and dispensed through regulated treatment programs. Dosing is individualized and gradually titrated, with take-home doses possible for stable patients under program rules.

Methadone is also used as a analgesic in some cases of chronic pain, especially when other opioids are not effective or poorly tolerated. Its pharmacokinetic profile, including a long and variable half-life, requires careful dosing and monitoring to minimize the risk of overdose and accumulation.

Safety and risks include the potential for dependence and overdose, particularly when combined with other central nervous system depressants such as benzodiazepines or alcohol. Methadone can prolong the QT interval and cause heart rhythm abnormalities at high doses. It can interact with various medications, and liver disease or other medical conditions can affect its metabolism. In pregnancy, methadone may be used under medical supervision to reduce withdrawal in the fetus, but it can lead to neonatal abstinence syndrome.

Regulation varies by country; methadone is a controlled substance in many jurisdictions. Prescribing and dispensing are typically restricted to authorized clinics or programs to minimize diversion and misuse, while aiming to provide consistent, evidence-based access to treatment.