opium,narcoticdrug that is obtained from the unripe seedpods of theopium poppy (Papaver somniferum), a plant of the familyPapaveraceae. (See poppy.) Opium is obtained by slightly incising the seed capsules of thepoppy after the plant’s flower petals have fallen. The slit seedpods exude a milkylatex that coagulates and changes colour, turning into a gumlike brown mass upon exposure to air. This raw opium may be ground into a powder, sold as lumps, cakes, or bricks, or treated further to obtain derivatives such asmorphine,codeine, andheroin. Opium and the drugs obtained from it are called opiates.

Opiumalkaloids

The pharmacologically active principles of opium reside in itsalkaloids, the most important of which,morphine,constitutes about 10 percent by weight of raw opium. Other active alkaloids such as papaverine andcodeine are present in smaller proportions. Opium alkaloids are of two types, depending on chemical structure and action. Morphine, codeine, andthebaine, which represent one type, act upon thecentral nervous system and areanalgesic, narcotic, and potentiallyaddicting compounds. Papaverine, noscapine (formerly called narcotine), and most of the other opium alkaloids act only to relax involuntary (smooth) muscles.

Physiological actions of opiates

Opiates (e.g., morphine, codeine, and thebaine) exert their main effects on thebrain andspinal cord. Their principal action is to relieve or suppresspain. The drugs alsoalleviateanxiety; induce relaxation, drowsiness, and sedation; and may impart a state of euphoria or otherenhanced mood. Opiates also have important physiological effects: they slow respiration and heartbeat, suppress the cough reflex, and relax thesmooth muscles of thegastrointestinal tract. Opiates are addictive drugs; they produce a physical dependence and withdrawal symptoms that can only beassuaged by continued use of the drug. With chronic use, the body develops a tolerance to opiates, so that progressively larger doses are needed to achieve the same effect. The higher opiates—heroin and morphine—are more addictive than opium or codeine. Opiates are classified as narcotics because they relieve pain, induce stupor andsleep, and produce addiction. The habitual use of opium produces physical and mental deterioration and shortens life. Anacute overdose of opium causes respiratory depression which can be fatal.

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drug use: Opium, morphine, heroin, and related synthetics

Opium was for many centuries the principal painkiller known tomedicine and was used in various forms and under various names.Laudanum, for example, was an alcoholic tincture (dilute solution) of opium that was used in European medical practice as an analgesic and sedative. Physicians relied onparegoric, a camphorated solution of opium, to treatdiarrhea by relaxing the gastrointestinal tract. The narcotic effects of opium are mainly attributable to morphine, which was first isolated about 1804. In 1898 it was discovered that treating morphine with acetic anhydride yieldsheroin, which is four to eight times as potent as morphine in both its pain-killing properties and its addictive potential. The other alkaloids naturally present in opium are much weaker; codeine, for example, is only one-sixth as potent as morphine and is used mainly for cough relief. Since the late 1930s, varioussynthetic drugs have been developed that possess the analgesic properties of morphine and heroin. These drugs, which includemeperidine (Demerol),methadone,levorphonal, and many others, are known as syntheticopioids. They have largely replaced morphine and heroin in thetreatment of severe pain.

Opiates achieve their effect on the brain because their structure closely resembles that of certain molecules calledendorphins, which are naturally produced in the body. Endorphins suppress pain andenhance mood by occupying certainreceptor sites on specificneurons (nerve cells) that are involved in the transmission of nervous impulses. Opiate alkaloids are able to occupy the same receptor sites, thereby mimicking the effects of endorphins in suppressing the transmission of pain impulses within thenervous system.

History of opium

The opium poppy was native to what is nowTurkey. AncientAssyrian herb lists and medical texts refer to both the opium poppy plant and opium, and in the 1st centuryce theGreek physicianDioscorides described opium in histreatiseDe materia medica, which was the leading Western text onpharmacology for centuries. The growth of poppies for their opium content spread slowly eastward fromMesopotamia andGreece. Apparently, opium was unknown in eitherIndia orChina in ancient times, and knowledge of the opium poppy first reached China about the 7th century. At first, opium was taken in the form of pills or was added to beverages. The oral intake of raw opium as a medicine does not appear to have produced widespread addictions in ancient Asian societies.

Opiumsmoking began only after the early Europeans inNorth America discovered the Indian practice ofsmoking tobacco in pipes. Some smokers began to mix opium with tobacco in their pipes, and smoking gradually became the preferred method of taking opium. Opium smoking was introduced into China fromJava in the 17th century and spread rapidly. The Chinese authorities reacted by prohibiting the sale of opium, but these edicts were largely ignored. During the 18th century European traders found in China an expanding and profitable market for the drug, and theopium trade enabled them to acquire Chinese goods such assilk andtea without having to spendprecious gold andsilver. Opium addiction became widespread in China, and the Chinese government’s attempts to prohibit the import of opium from British-ruled India brought it into direct conflict with the British government. As a result of their defeat in theOpium Wars, the Chinese were compelled to legalize the importation of opium in 1858. Opium addiction remained a problem in Chinese society until the Communists came to power in 1949 anderadicated the practice.

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In the West, opium came into wide use as a painkiller in the 18th century, and opium, laudanum, andparegoric were active ingredients in many patent medicines. These drugs were freely available without legal or medical restrictions, and the many cases of addiction they caused did not arouse undue social concern. Morphine was first isolated from opium about 1804, and the hypodermic syringe was invented at mid-century. Their use in combination on hundreds of thousands of sick or wounded American soldiers in theCivil War producedunprecedented numbers of addicts. Heroin, which was first synthesized in 1898, proved even more addictive than morphine, and by the early decades of the 20th century the legal use of opiates of any kind had been curtailed. The traffic in such drugs then went underground, leading to a vastillicit trade in heroin.

Although opium trade routes extending from the southeastern and southwestern regions of Asia closed temporarily duringWorld War II, cultivation of the plant continued and even prospered in areas of China. In 1948 Burma (Myanmar), located along the southwestern border of China, gained independence and soon after emerged as a major producer of the drug, paralleling the suppression of opium cultivation in China. Throughout the 1960s and ’70s,Southeast Asia experienced substantial growth in illicit opium trade. The border area shared by Myanmar,Laos, andThailand eventually became known as theGolden Triangle, a region that by the mid-1990s was the world’s leader in opium cultivation.

Smoking of opium declined in the 20th century, partly because it had been supplanted by more-potent derivatives and partly because of determined efforts in China and other developing countries toeradicate it. In the late 1990s, drug-control programs headed by theUnited Nations and by individual governments contributed to a reduction in opium poppy cultivation in the Golden Triangle. However, the region subsequently became a major producer of other illicit substances, includingmethamphetamines.

Also in the late 1990s, opium poppy cultivation increased inAfghanistan, and that country became a leading producer of heroin. As cultivation of the plant continued to soar there in the early 2000s, drug trade in the region became associated with terrorism and lawlessness. Near the end of the decade, however, increased law enforcement efforts and the outbreak of a poppyfungal disease caused poppy cultivation and opium production in Afghanistan to drop significantly. As a result, opium prices increased across the region, threatening to undermine the country’s illegal opium and heroin trade. The declines were seen as an opportunity to persuade local farmers tocultivate legal crops. Because of Internet pharmacies that sold the drug illegally, however, global opium trafficking remained high.

Thelegitimate use of certain opiate alkaloids in medicine hascompounded issues surrounding the cultivation of opium poppies. TodayP. somniferum is legally grown in some areas for the production of medicinal alkaloids. However, unlicensed cultivation of opium plants remains a serious legal offense in many countries, including theUnited States, since the substance is the starting product for heroin, which has millions of addicts worldwide.