Comparative Pharmacology
Head-to-head clinical analysis: DARVON versus DURAGESIC 75.
Peer-Reviewed Evidence
Head-to-head clinical analysis: DARVON versus DURAGESIC 75.
DARVON vs DURAGESIC-75
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Propoxyphene is a mu-opioid receptor agonist that inhibits ascending pain pathways by binding to opioid receptors in the CNS, altering pain perception. It also has weak local anesthetic effects.
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.
Propoxyphene hydrochloride (Darvon) for moderate to severe pain: 65 mg orally every 4 hours as needed; maximum 390 mg/day.
Adults: Apply one 75 mcg/hr transdermal patch every 72 hours. Start with lower dose in opioid-naive patients.
None Documented
None Documented
6-12 hours (parent drug); norpropoxyphene half-life 30-36 hours, accumulates with repeated dosing, increasing risk of toxicity.
22-25 hours after removal of patch; increased in elderly, hepatic/renal impairment
Primarily hepatic metabolism to norpropoxyphene, then renal excretion of metabolites; <20% excreted unchanged in urine; minor biliary/fecal elimination.
Renal (75% as metabolites, <10% unchanged), fecal (25%)
Category C
Category C
Opioid Analgesic
Opioid Analgesic