Codeine is a natural product found in the opium poppy (Papaver somniferum). An alkaloid of OPIUM, codeine can be separated from the other opium ALKALOIDS, purified, and used alone as an ANALGESIC (painkiller). It is however most often used along with mild nonopioid analgesics, such as aspirin, acetominophen, and ibuprofen. These combinations are particularly effective; the presence of the mild analgesics permits far lower codeine doses. Using lower doses of codeine has the advantage of reducing side effects, such as constipation. Codeine is one of the most widely used analgesics for mild to moderate pain.

Structurally, codeine is very similar to MOR-PHINE, differing only by the presence of a methoxy (-OCH₃) group at position 3, instead of morphine's hydroxy (-OH) group. The major advantage of codeine is its excellent activity when taken by mouth, unlike many opioid analgesics. Codeine itself has very low affinity for opioid receptors, yet it has significant analgesic potency. In the body, it is metabolized into morphine, and it is believed that the morphine generated from codeine is actually the active agent. Codeine has also been widely used as a cough suppressant. Codeine can be abused, and problems of abuse have often been linked to codeine-containing cough medicines, since they were once easily obtained over the counter. Chronic dosing with high codeine doses will produce TOLERANCE AND PHYSICAL DEPENDENCE, much like morphine.

Figure 1 Codeine

See Also

Papaver Somniferum)

Bibliography

REISINE, T., & PASTERNAK, G. (1996) Opioid analgesics and antagonists. In J. G. Hardman et al. (Eds.), The Pharmacological Basis of Therapeutics, 9th ed. (pp. 521-555). New York: McGraw-Hill.