Heroin ((INN) Diacetylmorphine , (BAN) diamorphine) is a semi-synthetic opioid. It is the 3,6-diacetyl derivative of morphine (hence diacetylmorphine) and is synthesised from it by acetylation. The white crystalline form is commonly the hydrochloride salt diacetylmorphine hydrochloride. It mimics endorphins and creates a sense of well-being upon entering the bloodstream (usually via intravenous injection). It is thus used both as a pain-killer and a recreational drug. Frequent administration has a high potential for causing addiction and may quickly lead to tolerance, especially as compared to other substances, though occasional use may not lead to symptoms of withdrawal. Internationally, heroin is controlled under Schedules I and IV of the Single Convention on Narcotic Drugs. It is illegal to manufacture, possess, or sell heroin in the United States; however, under the name diamorphine, heroin is a legal prescription drug in the United Kingdom.

Popular street names for heroin are gear, diesel, smack, B, skag, Bobby, black tar, horse, junk, jack, jenny, brown, brown sugar, dark, dope, dragon, bitch, gak, boy, and H.

History
The opium poppy was cultivated in lower Mesopotamia as long ago as 3400 BC. The chemical analysis of opium in the 19th century revealed that most of its activity could be ascribed to two ingredients, codeine and morphine.

Heroin 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.

However, as is often the case with scientific discovery, Wright’s invention did not lead to any further developments, and heroin’s fame would only begin to grow after it was independently re-synthesized 23 years later by another chemist, Felix Hoffmann. Hoffmann was working at the Bayer pharmaceutical company in Elberfeld, Germany, where the head of his laboratory was Heinrich Dreser. Dreser instructed Hoffmann to acetylate morphine, with the objective of producing codeine, a natural derivative of the opium poppy, similar to morphine but less potent and held to be less addictive. But instead of producing codeine, the experiment produced a substance that was actually three times more potent than morphine. Bayer would name the substance “heroin”, probably from the word heroisch, German for heroic, because in field studies people using the medicine felt “heroic”.

From 1898 through to 1910 heroin was marketed as a non-addictive morphine substitute and cough medicine for children. Bayer marketed heroin as a cure for morphine addiction before it was discovered that heroin is converted to morphine when metabolized in the liver. The company was somewhat embarrassed by this new finding and it became a historical blunder for Bayer.

As with aspirin, Bayer lost some of its trademark rights to heroin following the German defeat in World War I.

Usage and effects
Heroin is widely used as a (mostly) illegal drug for its intense euphoria, which often disappears with increased tolerance. It is thought that heroin’s popularity with recreational users, compared to morphine or other opiates, comes from its somewhat different perceived effects. These come from heroin’s high lipid solubility provided by the two acetyl groups, resulting in a very rapid penetration of the blood-brain barrier after use. Heroin can be taken or administered in a number of ways, including snorting and injection. It may also be smoked by inhaling the vapors produced when heated from below (known as “chasing the dragon”).

Many users dissolve the drug together with cocaine in a so-called “speedball” or “snowball”, which is injected intravenously. This causes an even more intense rush than heroin alone but is more dangerous because the short-acting stimulant with the longer-acting depressant increases the risk of overdosing on one or both drugs. Cocaine is an irritant to all bodily tissues, causing eventual necrosis at any site with which it is in frequent contact.

Once in the brain, heroin is rapidly metabolized into morphine by removal of the acetyl groups. It is the morphine molecule that then binds with opioid receptors and produces the subjective effects of the heroin high. Heroin is therefore a prodrug.

The onset of heroin’s effects is dependent on the method of administration. Taken orally, heroin is totally metabolized in vivo into morphine before crossing the blood-brain barrier; so the effects are the same as morphine also taken orally. Snorting heroin results in an onset within 10 to 15 minutes. Smoking heroin results in an almost immediate, though mild effect which strengthens the longer it is used. Intravenous injection results in rush and euphoria within 7 to 8 seconds; while intramuscular injection takes longer, having an effect within 5 to 8 minutes.

Heroin is a μ-opioid (mu-opioid) agonist. It acts on endogenous μ-opioid receptors that are spread in discrete packets throughout the brain, spinal cord and gut in almost all mammals. Heroin, along with other opioids, are agonists to four endogenous neurotransmitters. They are β-endorphin, dynorphin, leu-enkephalin, and met-enkephalin. The body responds to heroin in the brain by reducing (and sometimes stopping) production of the endogenous opioids when heroin is present. Endorphins are regularly released in the brain and nerves and attenuate pain. Their other functions are still obscure, but are probably related to the effects produced by heroin besides analgesia (antitussin, anti-diarrheal). The reduced endorphin production in heroin users creates a dependence on the heroin, and the cessation of heroin results in extremely uncomfortable symptoms including pain (even in the absence of physical trauma). This set of symptoms is called withdrawal syndrome. It has an onset 6 to 8 hours after the last dose of heroin.

Large doses of heroin can be fatal. The drug can be used for suicide or, as in the case of Sigmund Freud, physician-assisted suicide. Heroin can also be used as a murder weapon. The serial killer Dr. Harold Shipman used it on his victims. Dealers can also supply unwanted customers with unusually pure heroin, or heroin cut with other dangerous drugs such as fentanyl, resulting in a fatal overdose. It can sometimes be difficult to determine whether a heroin death was an accident, suicide or murder. The death of Joseph Krecker was such a case.

In Canada heroin is a controlled substance under Schedule I of the Controlled Drugs and Substances Act (CDSA). Every person who seeks or obtains heroin without disclosing authorization 30 days prior to obtaining another prescription from a practitioner is guilty of an indictable offence and liable to imprisonment for a term not exceeding seven years. Possession for purpose of trafficking is guilty of an indictable offence and liable to imprisonment for life.

In Hong Kong, heroin is regulated under Schedule 1 of Hong Kong’s Chapter 134 Dangerous Drugs Ordinance. It can only be used legally by health professionals and for university research purposes. It can be be given by pharmacists under a prescription. Anyone who supplies heroin without prescription can be fined $10000(HKD). The penalty for trafficking or manufacturing heroin is a $5,000,000 (HKD) fine and life imprisonment. Possession of heroin for consumption without license from the Department of Health is illegal with a $1,000,000 (HKD) fine and/or 7 years of jail time.