Comparative Pharmacology
Head-to-head clinical analysis: DARVON versus DURAGESIC 100.
Peer-Reviewed Evidence
Head-to-head clinical analysis: DARVON versus DURAGESIC 100.
DARVON vs DURAGESIC-100
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.
Pure opioid agonist that binds to mu-opioid receptors in the CNS, mimicking endogenous endorphins to inhibit pain transmission. Also interacts with kappa and delta receptors. Therapeutic effects include analgesia, sedation, and euphoria.
Propoxyphene hydrochloride (Darvon) for moderate to severe pain: 65 mg orally every 4 hours as needed; maximum 390 mg/day.
Transdermal patch; initial dose based on prior opioid use: for opioid-naive patients, 12 mcg/h every 72 hours; for opioid-tolerant patients, convert using equianalgesic tables; maximum dose 100 mcg/h per patch; apply to non-irritated, non-irradiated skin on chest, back, flank, or upper arm.
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 approximately 20–27 hours after transdermal system removal (range 13–25 hours in healthy adults; prolonged in elderly, hepatic impairment, and cachexia).
Primarily hepatic metabolism to norpropoxyphene, then renal excretion of metabolites; <20% excreted unchanged in urine; minor biliary/fecal elimination.
Renal (primarily as metabolites, <10% unchanged fentanyl); fecal (about 9% of dose).
Category C
Category C
Opioid Analgesic
Opioid Analgesic