Comparative Pharmacology
Head-to-head clinical analysis: DARVON versus ZOHYDRO ER.
Peer-Reviewed Evidence
Head-to-head clinical analysis: DARVON versus ZOHYDRO ER.
DARVON vs ZOHYDRO ER
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.
Zohydro ER is a pure opioid agonist with relative selectivity for mu-opioid receptors, although it can interact with other opioid receptors at higher doses. Its primary therapeutic action is analgesia via binding to mu-opioid receptors in the central nervous system, leading to activation of descending inhibitory pathways and modulation of pain perception.
Propoxyphene hydrochloride (Darvon) for moderate to severe pain: 65 mg orally every 4 hours as needed; maximum 390 mg/day.
Initial: 20 mg orally every 24 hours; titrate in increments of 10-20 mg every 3-7 days as needed; maximum dose 200 mg every 24 hours.
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 10.6 hours (range 8-17 hours) due to extended-release formulation; immediate-release hydromorphone half-life is 2-3 hours. Clinically, steady-state is achieved after 3-5 days of dosing.
Primarily hepatic metabolism to norpropoxyphene, then renal excretion of metabolites; <20% excreted unchanged in urine; minor biliary/fecal elimination.
Primarily renal excretion of hydromorphone-3-glucuronide (H3G, ~60%), unchanged hydromorphone (~15%), and other conjugates. Fecal excretion accounts for ~25%.
Category C
Category C
Opioid Analgesic
Opioid Analgesic