Comparative Pharmacology
Head-to-head clinical analysis: DARVON N W ASA versus ROXIPRIN.
Peer-Reviewed Evidence
Head-to-head clinical analysis: DARVON N W ASA versus ROXIPRIN.
DARVON-N W/ ASA vs ROXIPRIN
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
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.
Roxiprin is a combination analgesic containing rofecoxib (a COX-2 selective NSAID) and paracetamol (acetaminophen, a centrally acting analgesic/antipyretic). Rofecoxib inhibits prostaglandin synthesis by selectively blocking cyclooxygenase-2, reducing pain and inflammation. Paracetamol inhibits cyclooxygenase in the central nervous system and modulates descending serotonergic pathways, providing analgesia and antipyresis.
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.
500 mg orally every 6 to 8 hours as needed for pain or fever; maximum 2000 mg per day.
None Documented
None Documented
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).
2.5 hours (prolonged to 4-6 hours in hepatic impairment; no significant change in renal impairment)
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).
Renal (70% as unchanged drug, 20% as glucuronide conjugate); biliary/fecal (10%)
Category C
Category C
Opioid Analgesic Combination
Opioid Analgesic Combination