MT-45 is an opioid

Opioid

An opioid is a psychoactive chemical that works by binding to opioid receptors, which are found principally in the central and peripheral nervous system and the gastrointestinal tract...

 analgesic

Analgesic

An analgesic is any member of the group of drugs used to relieve pain . The word analgesic derives from Greek an- and algos ....

 drug invented in the 1970s by Dainippon Pharmaceutical Co. It is chemically a 1-substituted-4-(1,2-diphenylethyl)piperazine

Piperazine

Piperazine is an organic compound that consists of a six-membered ring containing two opposing nitrogen atoms. Piperazine exists as small alkaline deliquescent crystals with a saline taste....

 derivative, which is structurally unrelated to most other opioid drugs. Racemic MT-45 has around the same potency as 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...

, with almost all analgesic activity residing in the (S) enantiomer (interestingly the opposite stereochemistry from the related drug lefetamine

Lefetamine

Lefetamine is a drug which is a stimulant and also an analgesic with effects comparable to codeine.Lefetamine was invented in the 1930s and showed weak analgetic activity....

). It has been used as a lead compound

Lead compound

A lead compound in drug discovery is a chemical compound that has pharmacological or biological activity and whose chemical structure is used as a starting point for chemical modifications in order to improve potency, selectivity, or pharmacokinetic parameters.Lead compounds are often found in...

 from which a large family of potent opioid drugs have been developed, including full agonists, partial agonists and antagonists at the three main opioid receptor

Opioid receptor

Opioid receptors are a group of G protein-coupled receptors with opioids as ligands. The endogenous opioids are dynorphins, enkephalins, endorphins, endomorphins and nociceptin. The opioid receptors are ~40% identical to somatostatin receptors...

subtypes.