Codeine is a narcotic drug, one of two clinically useful phenanthrene alkaloids in opium. (The other is morphine.) Discovered
(1832) in opium by French chemist Pierre Jean Robiquet, codeine constitutes about 0.5 to 2.5 percent of this plant substance. The drug shares most of the pharmacologic characteristics of morphine but is only about one-tenth as potent on a weight-to-weight basis when given by injection. It loses one-third of its potency when taken orally.
Codeine is a frequently prescribed oral analgesic for
treatment of mild to moderate pain and can be used alone or in combination with salicylates, such as aspirin. It is also an
effective cough suppressant, at doses lower than those needed for treatment of pain, but it has been partly replaced by effective nonnarcotic, nonaddictive antitussives.
Codeine is addictive, capable of producing physical and psychological dependence and tolerance. Withdrawal symptoms are similar to, but milder than, those of morphine.