Nalbuphine
Nalbuphine (nalbuphine hydrochloride) is a synthetic opioid used commercially as an analgesic under a variety of trade names, including Nubain. It is noteworthy in part for the fact that at low dosages, it is found much more effective by women than by men, and may even increase pain in men.
Nalbuphine has been discontinued since 2003 in the UK.