Comparative Pharmacology
Head-to-head clinical analysis: CODAMINE versus DARVON N W ASA.
Peer-Reviewed Evidence
Head-to-head clinical analysis: CODAMINE versus DARVON N W ASA.
CODAMINE vs DARVON-N W/ ASA
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Codeine is an opioid agonist that binds to mu-opioid receptors in the CNS, inhibiting ascending pain pathways and altering pain perception. It is a prodrug converted to morphine via CYP2D6.
Propoxyphene is a weak opioid agonist that binds to mu-opioid receptors in the CNS, altering pain perception. Aspirin inhibits cyclooxygenase (COX-1 and COX-2), reducing prostaglandin synthesis, which mediates pain, fever, and inflammation.
Adults: 1-2 tablets (codeine 30 mg + acetaminophen 500 mg per tablet) orally every 4-6 hours as needed for pain; maximum 8 tablets per day.
1-2 capsules (propoxyphene napsylate 100 mg / aspirin 325 mg per capsule) orally every 4 hours as needed for pain; maximum 6 capsules per day.
None Documented
None Documented
Terminal elimination half-life: 4–6 hours in adults; prolonged to 8–12 hours in renal impairment (CrCl <30 mL/min)
Propoxyphene: terminal elimination half-life is 6-12 hours in adults with normal renal function; norpropoxyphene has a longer half-life (30-36 hours). Aspirin (as salicylate): half-life is dose-dependent, ranging from 2-3 hours at low doses to 15-30 hours at anti-inflammatory doses (300-600 mg in Darvon-N W/ASA).
Renal: 60% unchanged; Biliary/Fecal: 30% as metabolites; 10% other
Renal: propoxyphene and its metabolites (norpropoxyphene) are primarily eliminated via kidneys, with ~20-25% excreted unchanged; fecal: minor; biliary: some enterohepatic recirculation occurs, but exact % are not well quantified for the combination product. Aspirin is hydrolyzed to salicylate, which is excreted renally (75% as salicyluric acid, 10% as salicylic acid, 10% as glucuronide conjugates, and minor amounts as gentisic acid).
Category C
Category C
Opioid Analgesic Combination
Opioid Analgesic Combination