Comparative Pharmacology
Head-to-head clinical analysis: ACETAMINOPHEN AND CODEINE PHOSPHATE versus WESTADONE.
Peer-Reviewed Evidence
Head-to-head clinical analysis: ACETAMINOPHEN AND CODEINE PHOSPHATE versus WESTADONE.
ACETAMINOPHEN AND CODEINE PHOSPHATE vs WESTADONE
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Acetaminophen: centrally acting analgesic and antipyretic, possibly via inhibition of cyclooxygenase (COX) and modulation of cannabinoid receptors. Codeine: prodrug converted to morphine; mu-opioid receptor agonist.
Mu-opioid receptor agonist; also acts as an NMDA receptor antagonist and inhibits serotonin and norepinephrine reuptake.
One or two tablets (acetaminophen 300 mg/codeine 30 mg per tablet) orally every 4-6 hours as needed for pain; maximum 12 tablets daily.
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 (prolonged in hepatic impairment). Codeine: 2.5–3.5 hours; metabolites: morphine 1.5–2.5 hours, codeine-6-glucuronide 3–4 hours. Clinical context: dosing interval every 4–6 hours.
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.
Acetaminophen: renal elimination of conjugated metabolites (glucuronide 60%, sulfate 30%, cysteine/mercapturate <5%), less than 5% unchanged. Codeine: renal elimination of codeine (5–15%), morphine (5–10%), norcodeine (10–20%), and conjugates; 90% excreted in urine within 24 hours.
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