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Opioids are among the oldest therapies in our pharmacopeia, and clinicians recognize their universal utility to limit human distress from pain. Although opioids are widely used as potent analgesics, they have the potential for abuse because of their psychoactive properties. Although the therapeutic and toxic doses are difficult to predict because of the development of tolerance with chronic use, the primary adverse events from excessive dosing are respiratory depression and sedation.
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HISTORY AND EPIDEMIOLOGY
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The medicinal value of opium, the dried extract of the poppy plant Papaver somniferum, was first recorded circa 1500 B.C. in the Ebers papyrus. Raw opium is composed of at least 10% morphine, but extensive variability exists depending on the environment in which the poppy is grown.109 Although reformulated as laudanum (deodorized tincture of opium; 10 mg morphine/mL) by Paracelsus, paregoric (camphorated tincture of opium; 0.4 mg morphine/mL), Dover’s powder (pulvis Doveri), and Godfrey’s cordial in later centuries, the contents remained largely the same: phenanthrene poppy derivatives, such as morphine and codeine. Over the centuries since the Ebers papyrus, opium and its components have been used in two distinct manners: medically to produce profound analgesia and nonmedically to produce psychoactive effects.
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Currently, the widest clinical application of opioids is for acute or chronic pain relief. Opioids are available in various formulations that allow administration by virtually any route: epidural, inhalational, intranasal, intrathecal, oral, parenteral (ie, subcutaneous {SC}, intravenous {IV}, intramuscular {IM}), rectal, transdermal, and transmucosal. Patients also benefit from several of the presumed nonanalgesic effects produced by certain opioids. For example, codeine and hydrocodone are widely used as antitussives and loperamide as an antidiarrheal.
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Morphine was isolated from opium by Armand Séquin in 1804. Charles Alder Wright synthesized heroin from morphine in 1874. Ironically, the development and marketing of heroin as an antitussive agent by Bayer, the German pharmaceutical company, in 1898 legitimized the medicinal role of heroin.193 Subsequently, various xenobiotics with opioidlike effects were marketed, each promoted for its presumed advantages over morphine. However, in general, the purported advantages of such medications have fallen short of expectations, particularly with regard to their potential for abuse and addiction.
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Unfortunately, the history of opium and its derivatives is marred by humankind’s endless quest for xenobiotics that produce pleasurable effects. Opium smoking was so problematic in China by the 1830s that the Chinese government attempted to prohibit the importation of opium by the British East India Company. This act led to two Opium Wars between China and Britain. China eventually accepted the importation and sale of the drug and was forced to turn over Hong Kong to British rule. The euphoric and addictive potential of the opioids is immortalized in the works of several famous writers, such as Thomas de Quincey (Confessions of an English Opium Eater, 1821), Samuel Coleridge (The Rime of ...