Comparative Pharmacology
Head-to-head clinical analysis: CAPITAL AND CODEINE versus WESTADONE.
Peer-Reviewed Evidence
Head-to-head clinical analysis: CAPITAL AND CODEINE versus WESTADONE.
CAPITAL AND CODEINE vs WESTADONE
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Codeine is a prodrug converted to morphine, which acts as a mu-opioid receptor agonist, producing analgesia and CNS depression. Acetaminophen inhibits cyclooxygenase (COX) enzymes centrally, reducing prostaglandin synthesis and pain perception.
Mu-opioid receptor agonist; also acts as an NMDA receptor antagonist and inhibits serotonin and norepinephrine reuptake.
Acetaminophen 300 mg plus codeine phosphate 30 mg orally every 4 hours as needed for pain; maximum acetaminophen 3000 mg/day, codeine 180 mg/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 hours; Codeine-6-glucuronide: 2.5-3 hours; Morphine: 1.5-4.5 hours. Clinical context: In poor CYP2D6 metabolizers, half-life may be prolonged due to reduced clearance.
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: 90% (codeine and metabolites, primarily as codeine-6-glucuronide and norcodeine), Biliary/Fecal: <10%
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