Description of Heroin
Heroin is a crude preparation of diamorphine. It is a semisynthetic product obtained by acetylation of morphine, which occurs as a natural product in opium: the dried latex of certain poppy species (e.g. Papaver somniferum L.).
Diamorphine is a narcotic analgesic used in the treatment of severe pain. Illicit heroin may be smoked or solubilized with a weak acid and injected. Whereas opium has been smoked since historical times, diamorphine was first synthesized in the late nineteenth century.
Pharmacology Of Heroin
Diamorphine, like morphine and many other opioids, produces analgesia. It behaves as an agonist at a complex group of receptors that are normally acted upon by endogenous peptides known as endorphins.
Apart from analgesia, diamorphine produces drowsiness, euphoria and a sense of detachment. Negative effects include respiratory depression, nausea and vomiting, decreased motility in the gastrointestinal tract, suppression of the cough reflex and hypothermia. Tolerance and physical dependence occur on repeated use.
Cessation of use in tolerant subjects leads to characteristic withdrawal symptoms. Subjective effects following injection are known as ‘the rush’ and are associated with feelings of warmth and pleasure, followed by a longer period of sedation.
Diamorphine is 2-3 times more potent than morphine. The estimated minimum lethal dose is 200 mg, but addicts may be able to tolerate ten times as much.
Mode of use
Heroin from south-west Asia may be ‘smoked’ by heating the solid on a metal foil above a small flame and inhaling the vapor. Those intending to inject this form of heroin must first solubilise it with, for example, citric acid or ascorbic acid.
Heroin from south-east Asia is suitable for direct injection of a solution. A typical dose is 100 mg at street level purity. Except when used therapeutically as an analgesic drug, ingestion of diamorphine/heroin is a much less effective route of administration.