Description
Levacetylmethadol is an opioid drug belonging to the diphenylpropylamine class, chemically related to methadone. It is administered orally and was notable for its exceptionally long duration of action, which allowed for less frequent dosing compared to other opioid dependence treatments like methadone.Medical Uses
Levacetylmethadol was primarily indicated for the treatment of opioid dependence, specifically for maintenance therapy in individuals addicted to heroin or other opioids. Its long half-life, which permitted administration only two to three times per week, was considered an advantage over the daily dosing required for methadone in certain clinical settings, potentially improving patient compliance and reducing clinic visits.Pharmacology
- Mechanism of Action: Levacetylmethadol acts as a full agonist at the μ-opioid receptor. Its therapeutic effects, including the reduction of opioid withdrawal symptoms and cravings, are mediated through this interaction.
- Pharmacokinetics: Levacetylmethadol is a prodrug. It undergoes extensive metabolism in the liver to its active metabolites, primarily noracymethadol and dinoracymethadol, both of which also possess significant opioid activity. The very long elimination half-life of these active metabolites (reportedly 60-120 hours) is responsible for the drug's extended duration of action.
Side Effects
Common side effects associated with levacetylmethadol are typical of opioid agonists and include:- Nausea and vomiting
- Constipation
- Drowsiness
- Dizziness
- Sweating
- Headache
- Dry mouth
Serious Side Effects: A significant and ultimately market-withdrawing concern with levacetylmethadol was its potential to prolong the QT interval on an electrocardiogram. This QT prolongation carried a risk of serious, potentially life-threatening cardiac arrhythmias, including Torsades de Pointes. This cardiac risk was the primary factor leading to its withdrawal from the market.
Withdrawal from Market and Legal Status
Due to severe concerns regarding the risk of serious cardiac adverse events, particularly QT prolongation and the associated risk of fatal arrhythmias, levacetylmethadol was voluntarily withdrawn from the market by its manufacturer in the United States in 2001 and subsequently in several European countries.In the United States, Levacetylmethadol was initially classified as a Schedule II controlled substance under the Controlled Substances Act when it was medically available. Following its withdrawal from the market due to safety concerns and the lack of accepted medical use, it was reclassified as a Schedule I controlled substance. This classification indicates a high potential for abuse and no currently accepted medical use in treatment, placing it in the same category as drugs like heroin and LSD.
See Also
- Methadone
- Buprenorphine
- Opioid dependence
- QT interval prolongation