Analgesic activity and selectivity of isothiocyanate derivatives of fentanyl analogs for opioid receptors.

The analgesic activity and opioid receptor binding characteristics were studied for the isothiocyanate ohmefentanyl (OMFIT), and isothiocyanate carfentanil (CarFIT), isothiocyanate 4-methoxymethylfentanyl (MethoFIT), isothiocyanate 3-methylfentanyl (superFIT) and their amide analogs. Antinociceptive activity was evaluated using the mouse hot plate test; selectivity for opioid receptor was determined in bioassay and binding assay. SuperFIT, CarFIT, OMFIT and MethoFIT exhibited an analgesic ED50 lower than those of their parent compounds without isothiocyanate (SCN) group.