Comparative Pharmacology
Head-to-head clinical analysis: DARVON versus DURAGESIC 25.
Peer-Reviewed Evidence
Head-to-head clinical analysis: DARVON versus DURAGESIC 25.
DARVON vs DURAGESIC-25
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 mu-opioid receptor agonist that produces analgesia and sedation by mimicking endogenous opioids in the central nervous system.
Propoxyphene hydrochloride (Darvon) for moderate to severe pain: 65 mg orally every 4 hours as needed; maximum 390 mg/day.
Apply 25 mcg/hour transdermally every 72 hours; initial dose in opioid-naive patients: 25 mcg/hour is not recommended; use lower strength or immediate-release opioid first.
None Documented
None Documented
6-12 hours (parent drug); norpropoxyphene half-life 30-36 hours, accumulates with repeated dosing, increasing risk of toxicity.
Terminal elimination half-life 22-25 hours (range 13-31 h) after 72-h transdermal application; prolonged in elderly, hepatic or 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 (9%)
Category C
Category C
Opioid Analgesic
Opioid Analgesic