Comparative Pharmacology
Head-to-head clinical analysis: DARVON versus ONSOLIS.
Peer-Reviewed Evidence
Head-to-head clinical analysis: DARVON versus ONSOLIS.
DARVON vs ONSOLIS
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.
Onsolis (fentanyl buccal soluble film) is an opioid agonist that binds to mu-opioid receptors in the central nervous system, producing analgesia by increasing potassium conductance and inhibiting calcium channels, leading to reduced neurotransmitter release and hyperpolarization of neurons.
Propoxyphene hydrochloride (Darvon) for moderate to severe pain: 65 mg orally every 4 hours as needed; maximum 390 mg/day.
Onsolis (fentanyl buccal soluble film) is indicated for breakthrough pain in opioid-tolerant patients. The initial dose is 200 mcg placed on the buccal mucosa; titrate to effective dose in 200 mcg increments across subsequent episodes. Maximum frequency: 4 doses per day. Allow at least 2 hours between doses.
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 is approximately 3-5 hours in adults, providing sustained analgesic effect with multiple daily dosing.
Primarily hepatic metabolism to norpropoxyphene, then renal excretion of metabolites; <20% excreted unchanged in urine; minor biliary/fecal elimination.
Primarily hepatic metabolism via glucuronidation, with approximately 70% of the dose excreted in urine as metabolites and 10-15% in feces as unchanged drug.
Category C
Category C
Opioid Analgesic
Opioid Analgesic