Comparative Pharmacology
Head-to-head clinical analysis: DARVON N versus IONSYS.
Peer-Reviewed Evidence
Head-to-head clinical analysis: DARVON N versus IONSYS.
DARVON-N vs IONSYS
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.
IONSYS is an iontophoretic delivery system for fentanyl, a mu-opioid receptor agonist. Fentanyl binds to mu-opioid receptors in the CNS, inhibiting ascending pain pathways and altering pain perception and emotional response.
100 mg orally every 4 hours as needed for pain; maximum 600 mg per day.
Apply one 40 mcg fentanyl iontophoretic transdermal system to skin on upper arm or chest; delivers 40 mcg per dose on-demand for up to 24 hours or 80 doses, whichever is shorter. Maximum 2 doses per hour, 6 doses per application. Patient must be opioid-tolerant.
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: 16.3 ± 9.1 hours for fentanyl released from IONSYS; accounts for prolonged release from depot and is longer than intravenous fentanyl (3-12 hours).
Primarily renal (approximately 70% as unchanged drug and glucuronide conjugates); minor biliary/fecal elimination (25-30%).
Renal: approximately 90% as fentanyl metabolites (mainly norfentanyl) and less than 10% as unchanged drug; fecal: less than 10%.
Category C
Category C
Opioid Analgesic
Opioid Analgesic