Pharmacodynamic investigation of (+/-)-salutaridine.

The alkaloid 5,6,8,14-tetradehydro-4-hydroxy-3, 6-dimethoxy-17-methyl-morphinan-7-one[+/-)-salutaridine) was found to possess 3H-gamma-aminobutyric acid (3H-GABA) displacing activity (IC50 less than 1 mumol/l) in rat brain synaptic membranes. The enhancement of specific 3H-diazepam binding by increasing concentration of (+/-)-salutaridine follows a maximum curve indicating (+/-)-salutaridine to be a partial agonist at the GABA/benzodiazepine receptor complex.