Semorphone is an opiate

Opiate

In medicine, the term opiate describes any of the narcotic opioid alkaloids found as natural products in the opium poppy plant.-Overview:Opiates are so named because they are constituents or derivatives of constituents found in opium, which is processed from the latex sap of the opium poppy,...

 analogue that is an N-substituted derivative of oxymorphone

Oxymorphone

Oxymorphone or 14-Hydroxydihydromorphinone is a powerful semi-synthetic opioid analgesic first developed in Germany circa 1914, patented in the USA by Endo Pharmaceuticals in 1955 and introduced to the United States market in January 1959 and other countries around the same time...

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Semorphone is a partial agonist

Partial agonist

Partial agonists bind and activate a given receptor, but have only partial efficacy at the receptor relative to a full agonist...

 at μ-opioid

Mu Opioid receptor

The μ-opioid receptors are a class of opioid receptors with high affinity for enkephalins and beta-endorphin but low affinity for dynorphins. They are also referred to as μ opioid peptide receptors. The prototypical μ receptor agonist is the opium alkaloid morphine; μ refers to morphine...

 receptors. It is around twice the potency of morphine

Morphine

Morphine is a potent opiate analgesic medication and is considered to be the prototypical opioid. It was first isolated in 1804 by Friedrich Sertürner, first distributed by same in 1817, and first commercially sold by Merck in 1827, which at the time was a single small chemists' shop. It was more...

, but with a ceiling effect on both analgesia and respiratory depression which means that these effects stop becoming any stronger after a certain maximum dose.

It is not currently used in medicine, and is not a controlled drug, although it might be considered to be a controlled substance analogue

Federal Analog Act

The Federal Analog Act, , is a controversial section of the United States Controlled Substances Act which allowed any chemical "substantially similar" to a controlled substance listed in Schedule I or II to be treated as if it were also listed in those schedules, but only if intended for human...

 of oxymorphone on the grounds of its related chemical structure in some jurisdictions such as the USA, Canada

Canada

Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

, Australia

Australia

Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

 and New Zealand

New Zealand

New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

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