Comparative Pharmacology
Head-to-head clinical analysis: DARVOCET versus DARVON W ASA.
Peer-Reviewed Evidence
Head-to-head clinical analysis: DARVOCET versus DARVON W ASA.
DARVOCET vs DARVON W/ ASA
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Darvocet is a combination of propoxyphene, a mu-opioid receptor agonist that alters perception of and response to pain, and acetaminophen, which inhibits COX enzymes and modulates descending serotonergic pathways.
Combination analgesic: propoxyphene is a weak opioid agonist binding to mu-opioid receptors, inhibiting ascending pain pathways; aspirin irreversibly inhibits cyclooxygenase-1 and -2, reducing prostaglandin synthesis.
1 tablet (propoxyphene 100 mg / acetaminophen 650 mg) orally every 4 hours as needed for pain; maximum 6 tablets per day.
1 capsule (propoxyphene HCl 65 mg / aspirin 650 mg) orally every 4 hours as needed for pain, not to exceed 6 capsules per day.
None Documented
None Documented
Propoxyphene: 6-12 hours (parent), 30-36 hours (norpropoxyphene). Acetaminophen: 1-4 hours (therapeutic doses). Accumulation of norpropoxyphene occurs with repeated dosing.
Propoxyphene terminal half-life is 6–12 hours (mean 8 h) in healthy adults; prolonged in hepatic impairment or elderly due to reduced metabolism. Aspirin half-life is 15–20 minutes due to rapid hydrolysis to salicylate.
Propoxyphene: primarily hepatic metabolism to norpropoxyphene, renal excretion of metabolites (<1% unchanged). Acetaminophen: renal excretion of conjugates (85-90%) and unchanged drug (2-4%).
Renal elimination of propoxyphene and its metabolites accounts for ~70% of a dose, with ~20% excreted unchanged in urine; biliary/fecal elimination accounts for ~10%; aspirin is renally excreted as salicylate and its conjugates.
Category C
Category C
Opioid Analgesic Combination
Opioid Analgesic Combination