Comparative Pharmacology
Head-to-head clinical analysis: DARVOCET versus DARVOCET A500.
Peer-Reviewed Evidence
Head-to-head clinical analysis: DARVOCET versus DARVOCET A500.
DARVOCET vs DARVOCET A500
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: acetaminophen inhibits cyclooxygenase (COX) and modulates endocannabinoid system; propoxyphene is a mu-opioid receptor agonist.
1 tablet (propoxyphene 100 mg / acetaminophen 650 mg) orally every 4 hours as needed for pain; maximum 6 tablets per day.
One tablet (500 mg acetaminophen, 100 mg propoxyphene napsylate) orally every 4 hours as needed for pain; maximum 6 tablets 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: 6-12 hours (terminal, prolonged in elderly, hepatic impairment, or overdose). Acetaminophen: 2-3 hours (terminal, prolonged in hepatic impairment or overdose).
Propoxyphene: primarily hepatic metabolism to norpropoxyphene, renal excretion of metabolites (<1% unchanged). Acetaminophen: renal excretion of conjugates (85-90%) and unchanged drug (2-4%).
Propoxyphene: ~20-25% renal as unchanged drug, ~35% as norpropoxyphene, ~20% biliary/fecal. Acetaminophen: ~2-4% renal unchanged, ~85% as glucuronide and sulfate conjugates, ~5% as cysteine and mercapturate conjugates.
Category C
Category C
Opioid Analgesic Combination
Opioid Analgesic Combination