Comparative Pharmacology
Head-to-head clinical analysis: DARVON N versus ORAMORPH SR.
Peer-Reviewed Evidence
Head-to-head clinical analysis: DARVON N versus ORAMORPH SR.
DARVON-N vs ORAMORPH SR
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.
Morphine is a full opioid agonist with relative selectivity for the mu-opioid receptor, although it can interact with other opioid receptors at higher doses. Binding to mu-opioid receptors in the central nervous system (CNS) and peripheral tissues results in analgesia, euphoria, sedation, respiratory depression, and physical dependence. Morphine also activates descending inhibitory pathways and inhibits ascending nociceptive transmission.
100 mg orally every 4 hours as needed for pain; maximum 600 mg per day.
10-30 mg orally every 8-12 hours, sustained-release; titrate as needed for pain.
None Documented
None Documented
Propoxyphene: 6-12 hours; norpropoxyphene: 30-36 hours. Accumulation of norpropoxyphene on repeated dosing increases risk of toxicity.
2–4 hours in adults; in controlled-release formulation, effective half-life is prolonged due to sustained absorption. Clinically, steady-state is achieved in 1–2 days.
Primarily renal (approximately 70% as unchanged drug and glucuronide conjugates); minor biliary/fecal elimination (25-30%).
Renal (approximately 90% as morphine-3-glucuronide and morphine-6-glucuronide, minor amounts of unchanged morphine, and other conjugates); biliary/fecal (approximately 10%).
Category C
Category C
Opioid Analgesic
Opioid Analgesic