Comparative Pharmacology
Head-to-head clinical analysis: DARVON versus STADOL PRESERVATIVE FREE.
Peer-Reviewed Evidence
Head-to-head clinical analysis: DARVON versus STADOL PRESERVATIVE FREE.
DARVON vs STADOL PRESERVATIVE FREE
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.
Butorphanol is a synthetic agonist-antagonist opioid analgesic that exerts its effects primarily through binding to kappa-opioid receptors and, to a lesser extent, mu-opioid receptors, producing analgesia and sedation. It also has partial antagonist activity at mu receptors.
Propoxyphene hydrochloride (Darvon) for moderate to severe pain: 65 mg orally every 4 hours as needed; maximum 390 mg/day.
0.5–2 mg intravenously or intramuscularly every 3–4 hours as needed for pain. Alternatively, 1–2 mg as a single dose, may repeat in 30–60 minutes if needed.
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 2.5–3.3 hours in adults; prolonged to 4–6 hours in elderly or hepatic impairment.
Primarily hepatic metabolism to norpropoxyphene, then renal excretion of metabolites; <20% excreted unchanged in urine; minor biliary/fecal elimination.
Primarily hepatic metabolism (glucuronidation) to inactive metabolites; renal excretion accounts for <5% unchanged drug. Approximately 70% of dose excreted in urine as metabolites, 20% in feces.
Category C
Category C
Opioid Analgesic
Opioid Analgesic