Codeine (Also See Acetaminophen + Opioids)Rx

Last updated: October 29, 2014

Synonyms: Codeine sulfate, codeine phosphate

Drug Class: Narcotic analgesic

Preparations:  15-, 30-, 60 mg
Oral solution: 15 mg/5 mL

Dose: 15–30 mg q 4–6 h (maximum dose in 24 hours is 360 mg)

Indications: Pain not controlled by nonopioid drugs

Mechanism of Action: Binds to opioid receptors in CNS

Contraindications: Hypersensitivity to codeine, substance abuse, alcoholism, avoid in breastfeeding women, for postoperative pain in children who have undergone tonsillectomy, respiratory depression

Precautions: Use caution in patients with hypersensitivity to other opioids, respiratory disease, or renal or hepatic impairment. Decrease dose if hepatic or renal impairment.

Monitoring: Make sure drug is used to control pain.

Pregnancy Risk: C; D in high doses (fetal abstinence syndrome)

Adverse Effects
Common: Drowsiness, constipation, dysphoria, nausea
Less common: Rash, confusion,  CNS stimulation, insomnia, seizures, respiratory depression

Drug Interactions: Increased toxicity occurs with other CNS depressants. Avoid with MAOIs.

Patient Instructions: Drug is metabolized to morphine and is addictive. Use only to control pain. Do not use with alcohol or other CNS depressants.

Comments: Patients with low CYP2D6 activity (approximately 8% of the population) have a genetic inability to form morphine from codeine and derive no therapeutic effect from the drug. Patients with duplicate copies of CYP2D6 (fewer than 1%  of Caucasians but more common in populations of African ancestry) form more morphine from codeine – fatalities were  described in children after tonsillectomy and toxicity in breastfed infants of women who were CYP2D6 hypermetabolizers. Codeine is commonly administered as an acetaminophen/codeine combination (See Acetaminophen + Opioid).

Clinical Pharmacology: Codeine is  a prodrug that after oral absorption undergoes hepatic metabolism to morphine by CYP2D6; half-life of codeine and metabolites 3h,  urinary elimination as metabolites

Cost: $$

Cherny NI. Opioid analgesics. Comparative features and prescribing guidelines. Drugs 1996;51:713–737. PMID:8861543
Nuckols TK, Anderson L, Popescu I, et al. Opioid prescribing: a systematic review and critical appraisal of guidelines for chronic pain. Ann Intern Med 2014;160:38-47.PMID: 24217469.

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