levomethadyl acetate

Levomethadyl acetate (LAAM) is a synthetic opioid agonist with actions qualitatively similar to morphine (a prototypic mu agonist) and affecting the central nervous system (CNS) and smooth muscle. Principal actions include analgesia and sedation. Tolerance to these effects develops with repeated use. An abstinence syndrome generally occurs upon cessation of chronic administration similar to that observed with other opiates, but with slower onset, more prolonged course, and less severe symptoms. LAAM exerts its clinical effects in the treatment of opiate abuse through two mechanisms. First, LAAM cross-substitutes for opiates of the morphinetype, suppressing symptoms of withdrawal in opiate-dependent individuals. Second, chronic oral administration of LAAM can produce sufficient tolerance to block the subjective “high” of usual doses of parenterally administered opiates. Since the introduction of levomethadyl in 1995, the manufacturer has received increasing reports of severe cardiac-related adverse events, including QT interval prolongation, Torsades de Pointes and cardiac arrest. Other cardiac-related adverse events have also been reported, including arrhythmias, syncope, and angina. These events led to the removal of levomethadyl from the European market in March 2001. A very small number of patients may benefit from levomethadyl, but the risk of continued distribution and use no longer outweighs the overall benefits. — NCATS