Comparative Pharmacology
Head-to-head clinical analysis: CODEINE ASPIRIN APAP FORMULA NO 3 versus WESTADONE.
Peer-Reviewed Evidence
Head-to-head clinical analysis: CODEINE ASPIRIN APAP FORMULA NO 3 versus WESTADONE.
CODEINE, ASPIRIN, APAP FORMULA NO. 3 vs WESTADONE
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Codeine is a prodrug that is metabolized to morphine, a mu-opioid receptor agonist, which activates descending pain pathways and alters pain perception. Aspirin irreversibly inhibits cyclooxygenase-1 and -2, reducing prostaglandin synthesis and inflammation. Acetaminophen (APAP) acts centrally to inhibit cyclooxygenase and activate descending serotonergic pathways, though its exact mechanism is unclear.
Mu-opioid receptor agonist; also acts as an NMDA receptor antagonist and inhibits serotonin and norepinephrine reuptake.
1-2 tablets orally every 4-6 hours as needed for pain. Each tablet contains codeine 30 mg, aspirin 325 mg, acetaminophen 325 mg. Maximum: 12 tablets per day.
Oral: 2.5-10 mg every 4-6 hours as needed for pain; maximum 40 mg per day.
None Documented
None Documented
Codeine: 2.5-3.5 hours. Aspirin: 15-20 minutes for parent drug, but salicylate half-life is dose-dependent (2-3 hours at low doses, up to 15-30 hours at anti-inflammatory doses). Acetaminophen: 1.5-3 hours (prolonged in liver disease or overdose).
Terminal elimination half-life: 15-60 hours (mean ~24 hours). Clinical context: Prolonged half-life supports once-daily dosing in opioid maintenance; accumulation occurs with repeated dosing due to long half-life.
Codeine: Renal (up to 90% as metabolites, ~10% unchanged). Aspirin: Renal (75% as salicyluric acid, 10% as salicyl phenolic glucuronide, 5% as gentisic acid). Acetaminophen: Renal (85-90% as glucuronide/sulfate conjugates, 5-10% unchanged).
Primarily renal (40-50% as unchanged methadone and its metabolites, 15-20% as metadone-N-oxide), biliary/fecal (5-10%).
Category D/X
Category C
Opioid Agonist
Opioid Agonist