Comparative Pharmacology
Head-to-head clinical analysis: DARVON N versus DURAGESIC 12.
Peer-Reviewed Evidence
Head-to-head clinical analysis: DARVON N versus DURAGESIC 12.
DARVON-N vs DURAGESIC-12
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 synthetic opioid agonist that primarily binds to mu-opioid receptors in the central nervous system, leading to analgesic effects by increasing potassium conductance and decreasing calcium influx, thereby inhibiting ascending pain pathways and altering pain perception.
100 mg orally every 4 hours as needed for pain; maximum 600 mg per day.
Transdermal patch, initially 12 mcg/h applied every 72 hours in opioid-naive patients; titrate based on response and tolerance.
None Documented
None Documented
Propoxyphene: 6-12 hours; norpropoxyphene: 30-36 hours. Accumulation of norpropoxyphene on repeated dosing increases risk of toxicity.
Terminal elimination half-life is approximately 20–27 hours (range 13–44 hours) after transdermal patch removal; prolonged in elderly, hepatic impairment, and with continuous use due to drug accumulation in skin and adipose tissue.
Primarily renal (approximately 70% as unchanged drug and glucuronide conjugates); minor biliary/fecal elimination (25-30%).
Renal: approximately 75% as metabolites (primarily norfentanyl and other inactive metabolites) and <10% as unchanged fentanyl; fecal: approximately 9%; biliary: minor.
Category C
Category C
Opioid Analgesic
Opioid Analgesic