14-Methoxymetopon is an experimental opioid drug developed by a team led by Professor Helmut Schmidhammer at the University of Innsbruck in the mid-1990s.[1] It is a derivative of metopon in which a methoxy group has been inserted at the 14-position. It is a highly potent analgesic drug that is around 500 times stronger than morphine when administered systemically; however, when given spinally or supraspinally, it exhibits analgesic activity up to a million fold greater than morphine.[2] It binds strongly to the μ-opioid receptor and activates it to a greater extent than most similar opioid drugs.[3] This produces an unusual pharmacological profile, and although 14-methoxymetopon acts as a potent μ-opioid full agonist in regard to some effects such as analgesia, a ceiling effect is seen on other effects such as constipation and respiratory depression which is believed to involve interaction with the κ-opioid receptor[4]
^King MA, Su W, Nielan CL, Chang AH, Schütz J, Schmidhammer H, Pasternak GW (January 2003). "14-Methoxymetopon, a very potent mu-opioid receptor-selective analgesic with an unusual pharmacological profile". European Journal of Pharmacology. 459 (2–3): 203–9. doi:10.1016/S0014-2999(02)02821-2. PMID12524147.
^Mahurter L, Garceau C, Marino J, Schmidhammer H, Tóth G, Pasternak GW (October 2006). "Separation of binding affinity and intrinsic activity of the potent mu-opioid 14-methoxymetopon". The Journal of Pharmacology and Experimental Therapeutics. 319 (1): 247–53. doi:10.1124/jpet.106.105395. PMID16801454. S2CID26268795.