Comparative Pharmacology
Head-to-head clinical analysis: TYLENOL W CODEINE NO 1 versus WESTADONE.
Peer-Reviewed Evidence
Head-to-head clinical analysis: TYLENOL W CODEINE NO 1 versus WESTADONE.
TYLENOL W/ CODEINE NO. 1 vs WESTADONE
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Codeine is a prodrug that undergoes O-demethylation via CYP2D6 to morphine, which acts as a μ-opioid receptor agonist. Acetaminophen inhibits cyclooxygenase (COX) enzymes in the CNS, reducing prostaglandin synthesis and modulating pain perception.
Mu-opioid receptor agonist; also acts as an NMDA receptor antagonist and inhibits serotonin and norepinephrine reuptake.
Adult: 1-2 tablets (acetaminophen 300 mg/codeine 8 mg per tablet) orally every 4-6 hours as needed; maximum 8 tablets per day. Route: oral. Frequency: every 4-6 hours.
Oral: 2.5-10 mg every 4-6 hours as needed for pain; maximum 40 mg per day.
None Documented
None Documented
Acetaminophen: 2-3 hours; Codeine: 2.5-3.5 hours; Morphine (active metabolite): 2-4 hours. Terminal half-life prolonged in hepatic impairment or elderly.
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.
Renal: ~70-80% of codeine as inactive metabolites (codeine-6-glucuronide, norcodeine, morphine) and ~5-10% as unchanged codeine; ~5-15% of acetaminophen as unchanged drug. Biliary/fecal: minimal (<5% for both).
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