Comparative Pharmacology
Head-to-head clinical analysis: DARVON versus KADIAN.
Peer-Reviewed Evidence
Head-to-head clinical analysis: DARVON versus KADIAN.
DARVON vs KADIAN
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.
Mu-opioid receptor agonist; modulates pain perception and emotional response to pain.
Propoxyphene hydrochloride (Darvon) for moderate to severe pain: 65 mg orally every 4 hours as needed; maximum 390 mg/day.
20-100 mg orally every 12 hours; titration based on pain severity and prior opioid exposure.
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 morphine: 2–4 hours; KADIAN extended-release formulation: effective half-life ~12 hours due to prolonged absorption, dosing q12h or q24h
Primarily hepatic metabolism to norpropoxyphene, then renal excretion of metabolites; <20% excreted unchanged in urine; minor biliary/fecal elimination.
Renal: primarily as morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G); ~90% of total elimination is renal, with 10% biliary/fecal
Category C
Category C
Opioid Analgesic
Opioid Analgesic