It has a very long duration of action, with effects in animals seen for up to several weeks after administration of a single dose, although its binding to the KOR is not technically "irreversible" and its long-acting effects are instead caused by altered activity of c-Jun N-terminal kinases.
On ima veoma dugo vreme dejstva, sa efektima na životinjama primetnim do nekoliko nedelja nakon administracije jedne doze, mada njegovo vezivanje za kapa opioidni receptor nije nepovratno i njegovi dugotrajno dejstvo je umesto toga uzrokovano promenama aktivnosti c-Jun N-terminalne kinaze.