Comparative Pharmacology
Head-to-head clinical analysis: DARVON N versus ULTRAM ER.
Peer-Reviewed Evidence
Head-to-head clinical analysis: DARVON N versus ULTRAM ER.
DARVON-N vs ULTRAM ER
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.
Tramadol is a centrally acting synthetic opioid analgesic that binds to μ-opioid receptors and inhibits serotonin and norepinephrine reuptake.
100 mg orally every 4 hours as needed for pain; maximum 600 mg per day.
100 mg orally once daily initially, titrate up to 100 mg twice daily as needed; maximum 200 mg/day.
None Documented
None Documented
Propoxyphene: 6-12 hours; norpropoxyphene: 30-36 hours. Accumulation of norpropoxyphene on repeated dosing increases risk of toxicity.
The terminal elimination half-life of tramadol is approximately 6.3 hours (range 5-9 hours), while its active metabolite M1 has a half-life of about 7.4 hours. Clinically, this supports dosing every 24 hours for the extended-release formulation.
Primarily renal (approximately 70% as unchanged drug and glucuronide conjugates); minor biliary/fecal elimination (25-30%).
Renal excretion of tramadol and its metabolites accounts for approximately 90% of total elimination. About 10% is excreted unchanged, 30% as O-desmethyltramadol (M1), and the remainder as other minor metabolites. Biliary/fecal excretion is minimal (<10%).
Category C
Category C
Opioid Analgesic
Opioid Analgesic