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Samidorphan structure.svg
Pharmacokinetic data
Biological half-life 7-9 hours[1]
CAS Number 852626-89-2 YesY
PubChem CID: 11667832
ChemSpider 23259667
UNII 7W2581Z5L8 YesY
KEGG D10162 YesY
Chemical data
Formula C21H26N2O4
Molecular mass 370.441 g/mol

Samidorphan (ALKS-33) is a selective opioid antagonist which blocks the μ-opioid receptor, but without blocking δ-opioid or κ-opioid receptors. It has been investigated for the treatment of alcoholism and cocaine addiction,[2][3] showing similar efficacy to naltrexone but possibly with reduced side effects.

However, it has attracted much more attention as part of the combination product ALKS-5461, where samidorphan is combined with the mixed μ-opioid agonist and κ-opioid antagonist opioid modulator buprenorphine, as an antidepressant. Buprenorphine has shown antidepressant effects in some human studies, thought to be because of its antagonist effects at the κ-opioid receptor, but has not been further developed for this application because of its μ-opioid agonist effects and consequent abuse potential. By combining buprenorphine with samidorphan to block the μ-opioid agonist effects, the combination acts more like a selective κ-opioid antagonist, and produces only antidepressant effects, without typical μ-opioid effects being evident.[4][5]

It is also being studied in combination with olanzapine, as ALKS-3831, for use in schizophenia.[6] It is hoped it will be effective while resulting in less weight gain. Phase 2 studies have begun.[7]

See also[edit]