Frakefamide is a potent analgesic that functions as a peripheral active μ-selective receptor agonist. It cannot penetrate the blood-brain barrier to enter the central nervous system.

Frakefamide yields a dose-dependent increase in morphine appropriate responding to 50% at the highest dose tested (10 μmol/kg) after infusion durations of 2 min. Whereas after 15 min infusions a maximum of 25% morphine appropriate responding was occasioned at 17.5 μmol/kg [1,2].