Evaluating the Safety of Acute Baclofen in Methadone-maintained Individuals With Opiate Dependence.

Baclofen is the only selective GABA-B agonist licensed for human use. Originally developed as a potential anti-epileptic in the 1920s, it was found to have anti-spastic effects and is currently used for the treatment of spastic movement, especially in instances of spinal cord injury, spastic diplegia, multiple sclerosis, and amyotrophic lateral sclerosis.

Placebo tablets will be vitamin D3, (colecalciferol).