Comparative Pharmacology
Head-to-head clinical analysis: TYLENOL W CODEINE NO 2 versus WESTADONE.
Peer-Reviewed Evidence
Head-to-head clinical analysis: TYLENOL W CODEINE NO 2 versus WESTADONE.
TYLENOL W/ CODEINE NO. 2 vs WESTADONE
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Acetaminophen: Inhibits cyclooxygenase (COX) in the CNS, reducing prostaglandin synthesis, with weak peripheral COX inhibition. Codeine: Prodrug converted to morphine via CYP2D6; morphine acts as a mu-opioid receptor agonist, inhibiting ascending pain pathways and altering pain perception.
Mu-opioid receptor agonist; also acts as an NMDA receptor antagonist and inhibits serotonin and norepinephrine reuptake.
1 to 2 tablets (300 mg acetaminophen/15 mg codeine phosphate per tablet) orally every 4 hours as needed for pain; 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
Acetaminophen: 2-3 hours. Codeine: 2.5-3.5 hours. In hepatic impairment, half-life of codeine may be prolonged.
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% as glucuronide and sulfate conjugates of acetaminophen, 5-10% as unchanged acetaminophen, and 5-10% as unchanged codeine. Biliary/fecal: minor, <5%.
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