API

Acetylsalicylic acid, codeine phosphate

Drug classification

Acetylsalicylic acid: Analgesic (NSAID); Codeine phosphate: Analgesic (opioid); Combination: Analgesic.

Dosage form

Tablet

API strength per dosage

acetylsalicylic acid codeine phosphate…

Dose

Adults: 1–2 tablets every 4–6 hours as needed; maximum 8 tablets in 24 hours. Not recommended for children under 16 years. Use with caution in elderly and those with hepatic or renal impairment; dose adjustment may be required. Contraindicated in pregnancy, breastfeeding, and certain comorbidities.

Mechanism of action

Acetylsalicylic acid irreversibly inhibits cyclooxygenase-1 and -2 (COX-1, COX-2), reducing prostaglandin and thromboxane synthesis; codeine phosphate is a μ-opioid receptor (MOR) agonist, inhibiting nociceptive neurotransmission and increasing pain threshold via G-protein-coupled receptor signaling.

Indications

Mild to moderate pain, headache, migraine, neuralgia, toothache, dysmenorrhea, musculoskeletal pain, postoperative pain, fever unresponsive to other measures.

Side effects

Gastrointestinal bleeding, peptic ulcer, nausea, vomiting, constipation, dizziness, drowsiness, respiratory depression, hypersensitivity reactions, renal impairment, hepatotoxicity, confusion, dependence, tinnitus, bronchospasm.

Pregnancy category

Category D

Precautions

Hypersensitivity to salicylates or opioids, history of peptic ulcer or GI bleeding, bleeding disorders, severe hepatic or renal impairment, respiratory depression, asthma, pregnancy, breastfeeding, concurrent CNS depressants, alcohol use, children with viral infections (risk of Reye’s syndrome), elderly, risk of dependence or misuse.

Contraindications

Hypersensitivity to salicylates, codeine, or NSAIDs, active peptic ulcer, severe hepatic or renal impairment, respiratory depression, acute asthma, children under 12, breastfeeding, known CYP2D6 ultra-rapid metabolizers.