R-5260 is an opioid drug from the orphine series, which is a derivative of the opioid analgesic norpipanone, but with the piperidine ring fused with a spiro heterocycle. It was discovered by Janssen Pharmaceutica, and is a highly potent opioid around 10x the potency of fentanyl in a rodent model of analgesia undertaken before the MOR and NOP receptors had been differentiated. It is related to other potent opioid derivatives such as dipipanone, bezitramide, R-4066 and spirochlorphine, and is also related to dopamine antagonist neuroleptic drugs such as spiperone and fluspirilene, although R-5260 does not have any dopamine antagonist activity itself. See also Spirodecanone References