Comparative Pharmacology
Head-to-head clinical analysis: ABSTRAL versus DARVON.
Peer-Reviewed Evidence
Head-to-head clinical analysis: ABSTRAL versus DARVON.
ABSTRAL vs DARVON
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Fentanyl is a potent mu-opioid receptor agonist, producing analgesia and sedation by activating G-protein coupled opioid receptors in the central nervous system.
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.
For breakthrough pain in opioid-tolerant patients: initial dose 100 mcg sublingual tablet, titrate across strengths (100, 200, 300, 400, 600, 800 mcg) as needed; maximum 2 doses per episode, minimum 2 hours between episodes.
Propoxyphene hydrochloride (Darvon) for moderate to severe pain: 65 mg orally every 4 hours as needed; maximum 390 mg/day.
None Documented
None Documented
Terminal elimination half-life: 6-10 hours (mean 8 hours); prolonged in elderly and hepatic impairment
6-12 hours (parent drug); norpropoxyphene half-life 30-36 hours, accumulates with repeated dosing, increasing risk of toxicity.
Renal: ~70% as metabolites (primarily fentanyl conjugates and norfentanyl), ~10% unchanged; Fecal: ~9%; Biliary: minimal
Primarily hepatic metabolism to norpropoxyphene, then renal excretion of metabolites; <20% excreted unchanged in urine; minor biliary/fecal elimination.
Category C
Category C
Opioid Analgesic
Opioid Analgesic