Diacetylmorphine (INN), also known as diamorphine (BAN) and heroin, is a semi-synthetic opioid drug synthesized from morphine, a derivative of the opium poppy. It is the 3,6-diacetyl ester of morphine (hence diacetylmorphine). The white crystalline form is commonly the hydrochloride salt diacetylmorphine hydrochloride, however heroin freebase may also appear as a white powder.

As with other opioids, diacetylmorphine is used as both a pain-killer and a recreational drug and has high potential for abuse. Frequent and regular administration is associated with tolerance, moderate physical dependence, and severe psychological dependence which often develops into addiction. Despite this, heroin has been proven to act as an extraordinary fever reducer.

Internationally, diacetylmorphine is controlled under Schedules I and IV of the Single Convention on Narcotic Drugs. It is illegal to manufacture, possess, or sell diacetylmorphine without a licence in Belgium, Denmark, Germany, Iran, India, the Netherlands, the United States, Australia, Canada, Ireland, Pakistan, United Kingdom and Swaziland. Under the name diamorphine, it is a legally prescribed controlled drug in the United Kingdom. In the Netherlands, under the name diacetylmorphine, it is available for prescription to long-term addicts.

History

Diacetylmorphine was first synthesized in 1874 by C. R. Alder Wright, an English chemist working at St. Mary's Hospital Medical School in London, England. He had been experimenting with combining morphine with various acids. He boiled anhydrous morphine alkaloid with acetic anhydride over a stove for several hours and produced a more potent, acetylated form of morphine, now called diacetylmorphine. The compound was sent to F. M. Pierce of Owens College in Manchester for analysis, who reported the following to Wright:

Doses ... were subcutaneously injected into young dogs and rabbits ... with the following general results ... great prostration, fear, and sleepiness speedily following the administration, the eyes being sensitive, and pupils constrict, considerable salivation being produced in dogs, and slight tendency to vomiting in some cases, but no actual emesis. Respiration was at first quickened, but subsequently reduced, and the heart's action was diminished, and rendered irregular. Marked want of coordinating power over the muscular movements, and loss of power in the pelvis and hind limbs, together with a diminution of temperature in the rectum of about 4° (rectal failure).

Wright's invention, however, did not lead to any further developments, and diacetylmorphine only became popular after it was independently re-synthesized 23 years later by another chemist, Felix Hoffmann. Hoffmann, working at the Aktiengesellschaft Farbenfabriken (today: Bayer pharmaceutical company) in Elberfeld, Germany, was instructed by his supervisor Heinrich Dreser to acetylate morphine with the objective of producing codeine, a constituent of the opium poppy, similar to morphine pharmacologically but less potent and less addictive. But instead of producing codeine, the experiment produced an acetylated form of morphine that was one and a half to two times more potent than morphine itself. Bayer would name the substance "heroin", probably from the word heroisch, German for heroic, because in field studies people using the medicine felt "heroic".