Comparative Pharmacology
Head-to-head clinical analysis: DARVON N versus DURAGESIC 75.
Peer-Reviewed Evidence
Head-to-head clinical analysis: DARVON N versus DURAGESIC 75.
DARVON-N vs DURAGESIC-75
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Propoxyphene is a weak mu-opioid receptor agonist that produces analgesia by binding to opioid receptors in the central nervous system, altering the perception of and response to pain. Its metabolite norpropoxyphene has local anesthetic and sodium channel blocking effects, which may contribute to cardiac toxicity.
Fentanyl is a potent opioid agonist primarily at the mu-opioid receptor, exerting its analgesic effects by mimicking endogenous endorphins and enkephalins to activate G-protein-coupled inwardly rectifying potassium channels, leading to hyperpolarization and reduced neuronal excitability in pain pathways.
100 mg orally every 4 hours as needed for pain; maximum 600 mg per day.
Adults: Apply one 75 mcg/hr transdermal patch every 72 hours. Start with lower dose in opioid-naive patients.
None Documented
None Documented
Propoxyphene: 6-12 hours; norpropoxyphene: 30-36 hours. Accumulation of norpropoxyphene on repeated dosing increases risk of toxicity.
22-25 hours after removal of patch; increased in elderly, hepatic/renal impairment
Primarily renal (approximately 70% as unchanged drug and glucuronide conjugates); minor biliary/fecal elimination (25-30%).
Renal (75% as metabolites, <10% unchanged), fecal (25%)
Category C
Category C
Opioid Analgesic
Opioid Analgesic