Pierre-Jean Robiquet (1780–1840), Friedrich Wilhelm Sertürner (1783–1841)
Morphine was isolated from opium in 1806 by Friedrich Wilhelm Sertürner, an obscure German apprentice apothecary. Codeine was extracted from the same plant in 1832 by Pierre-Jean Robiquet, a highly distinguished French pharmacist and professor of chemistry at the École de Pharmacie in Paris. Although this was considered Robiquet’s most significant scientific accomplishment, in 1805 he had identified the chemical structure of asparagine, the first amino acid; and in 1826 he had isolated the alizarin red dye from madder root.
Codeine, the second most important of the twenty alkaloids derived from the opium poppy, may be considered a diminutive first cousin of morphine. Relative to morphine, codeine is a less effective analgesic that produces less sedation and is less prone to abuse. However, codeine is no second-class drug. Codeine is the most commonly used opioid (morphine-like drug) in the world. Most codeine used for medical purposes is manufactured from morphine in laboratories and is usually taken by mouth alone or in combination with aspirin or acetaminophen (paracetamol) for relief of mild-to-moderate pain. Codeine is also an effective antitussive (cough suppressant) but has been largely supplanted by dextromethorphan (DM), a drug with fewer side effects and far lower abuse potential.
Codeine’s similarity to morphine is not surprising, as codeine (a.k.a. 3-methylmorphine) is converted in the body to morphine. However, 7–10 percent of the Caucasian population has a genetic defect that renders the enzyme responsible for the conversion nonfunctional, and for these individuals, codeine is ineffective at normal doses. Conversely, some 1–3 percent of whites and more than 25 percent of Ethiopians are born with an enzyme that is ultra-active in converting codeine to morphine. For them, normal doses of codeine can lead to a buildup of excessive levels of morphine, increasing the risk of toxicity.
SEE ALSO Opium (c. 2500 BCE), Alkaloids (1806), Morphine (1806), Heroin (1898), Aspirin (1899), Drug Metabolism (1947), Acetaminophen/Paracetamol (1953), Dextromethorphan (1958), Opioids (1973).
When codeine is used with other drugs in cough and cold products, it is often dissolved in flavored syrups in order to mask its unpalatable taste.