Generic & Brand Names
Generic: Codeine (usually as Codeine Phosphate)
Common Brands: Codeine Phosphate®, Codalgin®, Co-codamol® (combination)
Drug Class
Opioid Analgesic Antitussive Mechanism of Action
Codeine is a weak opioid that acts on μ-opioid receptors. It is metabolized in the liver to morphine, which produces analgesic and antitussive effects by suppressing the cough center and altering pain perception.
Indications
- Mild to moderate pain
- Dry, distressing cough (restricted use)
- Often used in combination with paracetamol
Dosage (General)
- Adults (pain): 30–60 mg every 4–6 hours (max 240 mg/day)
- Adults (cough): 10–20 mg every 4–6 hours
- Children: Not recommended due to safety concerns
Dose adjustments required in renal/hepatic impairment.
Side Effects
- Drowsiness and sedation
- Nausea and vomiting
- Constipation
- Dizziness
- Respiratory depression (dose-related)
Contraindications & Precautions
- Children under 12 years
- Post-tonsillectomy/adenoidectomy patients
- Respiratory depression or acute asthma
- Ultra-rapid CYP2D6 metabolizers
- Risk of dependence with prolonged use
Drug Interactions
- Alcohol and sedatives (↑ CNS depression)
- Benzodiazepines
- Other opioids
- MAO inhibitors
Pregnancy & Lactation
Avoid during pregnancy if possible. Contraindicated during breastfeeding due to risk of opioid toxicity in infants.
Key Notes
- Risk of misuse and dependence
- Restricted or banned for pediatric cough in many countries
- Use lowest effective dose for shortest duration
References
- British National Formulary (BNF). Opioid analgesics – Codeine.
- British National Formulary for Children (BNFc). Analgesics and antitussives.
- Kliegman RM, St. Geme JW. Nelson Textbook of Pediatrics, 22nd ed. Elsevier; Opioid safety chapter.
- Katzung BG, Trevor AJ. Basic & Clinical Pharmacology, 15th ed.