Comparative Pharmacology
Head-to-head clinical analysis: DARVON versus PROPHENE 65.
Peer-Reviewed Evidence
Head-to-head clinical analysis: DARVON versus PROPHENE 65.
DARVON vs PROPHENE 65
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.
Propoxyphene is a weak opioid agonist that binds to mu-opioid receptors in the CNS, inhibiting ascending pain pathways and altering perception of pain. It also has local anesthetic and moderate antitussive effects.
Propoxyphene hydrochloride (Darvon) for moderate to severe pain: 65 mg orally every 4 hours as needed; maximum 390 mg/day.
Propoxyphene napsylate 100 mg orally every 4 hours as needed for pain; maximum 600 mg/day.
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 of propoxyphene: 6-12 hours (mean ~8 hours); norpropoxyphene half-life: 22-36 hours, leading to accumulation with chronic dosing. Clinical context: prolonged half-life in elderly and hepatic impairment increases risk of toxicity.
Primarily hepatic metabolism to norpropoxyphene, then renal excretion of metabolites; <20% excreted unchanged in urine; minor biliary/fecal elimination.
Renal elimination of unchanged drug and metabolites: propoxyphene and its major metabolite norpropoxyphene account for ~20-30% as unchanged drug in urine; remainder as conjugated metabolites. Biliary/fecal elimination accounts for <10%.
Category C
Category C
Opioid Analgesic
Opioid Analgesic