Comparative Pharmacology
Head-to-head clinical analysis: FENTANYL 75 versus WESTADONE.
Peer-Reviewed Evidence
Head-to-head clinical analysis: FENTANYL 75 versus WESTADONE.
FENTANYL-75 vs WESTADONE
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Fentanyl is a mu-opioid receptor agonist, producing analgesia and sedation by activating G-protein coupled opioid receptors in the central nervous system, leading to decreased neurotransmitter release and hyperpolarization of neurons.
Mu-opioid receptor agonist; also acts as an NMDA receptor antagonist and inhibits serotonin and norepinephrine reuptake.
Apply 75 mcg/h transdermally every 72 hours for opioid-tolerant patients; not for acute pain. Rotate application site.
Oral: 2.5-10 mg every 4-6 hours as needed for pain; maximum 40 mg per day.
None Documented
None Documented
Terminal elimination half-life: 3-12 hours (mean ~7 hours); prolonged in elderly, hepatic impairment, or continuous infusion.
Terminal elimination half-life: 15-60 hours (mean ~24 hours). Clinical context: Prolonged half-life supports once-daily dosing in opioid maintenance; accumulation occurs with repeated dosing due to long half-life.
Renal: ~75% as metabolites (primarily norfentanyl) and ~10% unchanged; fecal: ~9%; biliary: minor.
Primarily renal (40-50% as unchanged methadone and its metabolites, 15-20% as metadone-N-oxide), biliary/fecal (5-10%).
Category D/X
Category C
Opioid Agonist
Opioid Agonist