Comparative Pharmacology
Head-to-head clinical analysis: DARVON N versus LAZANDA.
Peer-Reviewed Evidence
Head-to-head clinical analysis: DARVON N versus LAZANDA.
DARVON-N vs LAZANDA
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Propoxyphene is a weak mu-opioid receptor agonist that produces analgesia by binding to opioid receptors in the central nervous system, altering the perception of and response to pain. Its metabolite norpropoxyphene has local anesthetic and sodium channel blocking effects, which may contribute to cardiac toxicity.
Fentanyl is a μ-opioid receptor agonist. It binds to μ-opioid receptors in the central nervous system, activating G-protein-coupled receptors to inhibit adenylate cyclase, reduce cAMP production, and modulate ion channels, leading to decreased neurotransmitter release (e.g., substance P, glutamate) and hyperpolarization of neurons, resulting in analgesia and sedation.
100 mg orally every 4 hours as needed for pain; maximum 600 mg per day.
100 mcg (one spray) intranasally as needed for breakthrough pain; may repeat once after 15-30 minutes if needed; do not exceed 2 doses per episode and 4 doses per day.
None Documented
None Documented
Propoxyphene: 6-12 hours; norpropoxyphene: 30-36 hours. Accumulation of norpropoxyphene on repeated dosing increases risk of toxicity.
Terminal elimination half-life: 6–10 hours (mean approximately 7 hours) following nasal administration; prolonged in hepatic impairment.
Primarily renal (approximately 70% as unchanged drug and glucuronide conjugates); minor biliary/fecal elimination (25-30%).
Renal excretion of metabolites (mostly fentanyl metabolites, primarily norfentanyl): approximately 75%; fecal excretion: approximately 9%; less than 10% excreted as unchanged fentanyl in urine.
Category C
Category C
Opioid Analgesic
Opioid Analgesic