Codeine [Methylmorphine]

This chapter discusses codeine (methylmorphine), a neuropsychotropic drug. It presents the approved indications of the drug for neuropsychological disorders, usual dosage and administration, available dosage forms, storage, and compatibility, and the mechanism of action. Information on relative contraindications, clinically significant drug interactions, adverse drug reactions, and overdosage is also provided. Sold under the trade names Codeine Contin^® and Paverai^®, codeine is prescribed for mild to moderate pains. The codeine extended-release formulation (Codeine Contin^®) is indicated for the long-term symptomatic management of moderate cancer pain. Codeine appears to elicit its analgesic action primarily by binding to the endorphin receptors in the CNS. This binding to receptors is thought to result in the inhibition of neurotransmission in the ascending pain pathways and in diminished pain perception. However, the exact mechanism of action has not yet been fully determined. Relative contraindications include acute alcoholism and severe CNS depression.