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Morphine

pain heroin opium properties

Morphine, C17H19NO3 • H2O, is a narcotic analgesic drug used primarily in medicine for its pain killing properties. Morphine was isolated from opium in 1805 and named for Morpheus, the Greek god of sleep, by the German chemist and pharmacist Friedrich W. Sertürner (1783-1841). Morphine is the principle and most active alkaloid obtained from the unripe seed capsules of the opium poppy, Papaver somniferum. There is evidence that morphine was ingested, in the form of opium, thousands of years B.C. Morphine can be synthesized in a laboratory but because it is difficult to do so, the medical industry relies on countries that produce opium such as India and Turkey for their morphine supply. The drug occurs as a white crystalline powder or colorless crystals and is available for legal medical use. Morphine and synthetically made morphine-like drugs are most often given to people who have pain caused by physical trauma, or those who have intense pain caused by diseases such as cancer.

Morphine has similar painkilling properties to endorphins and enkephalins, a group of amino acid compounds produced in the pituitary gland. The molecular structure of morphine is so much like that of endorphins that it is able to bind to and occupy specialized receptor sites located in various pain centers in the central nervous system. Morphine also alters the release of neurotransmitters. The perception of pain is thus changed and the emotional reaction to pain (fear of, or anticipation of pain) is also affected. Morphine also affects the bowel and causes constipation. One's pain threshold is elevated by morphine's ability to induce an extreme state of relaxation. Other effects of morphine include drowsiness, slowing of respiration, cough suppression, changes in the endocrine and autonomic nervous systems, nausea, and vomiting. The most serious side effect of morphine, as with other drugs derived from opium, is its addictiveness. For this reason, scientists have strived to synthesize drugs that mimic the painkilling attributes of morphine but do not have the same addictive properties. Two semi-synthetic drugs that can be made from morphine are codeine, which is used for pain relief and cough suppression, and diacetylmorphine or heroin, an extremely potent and addictive drug.

Developed by the Bayer Company of Germany in 1898, heroin is obtained by treating morphine with acetic anhydride. Heroin, which is four to eight times as potent as morphine, was originally used as a cough suppressant and narcotic analgesic but proved to be even more addictive and have worse side effects than morphine and codeine. Although heroin is converted into morphine in the body, it acts on the brain faster than morphine. Heroin has greater lipid solubility and is able to cross the blood-brain barrier more easily. In the United States, heroin was sold over-the-counter as a cough suppressant until 1917. Because of its exceptional pain killing properties, heroin abuse has been a problem since it was discovered; however, addiction to heroin was not prevalent until after World War II. Today, the use and trafficking of heroin are a major problem throughout the world.

Resources

Books

Goodman and Gilman. The Pharmacological Basis of Therapeutics. 6th ed. New York: Macmillan, 1980.

Lewington, Anna. Plants For People. New York: Oxford University Press, 1990.

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