Comparative Pharmacology
Head-to-head clinical analysis: FENTANYL 12 versus WESTADONE.
Peer-Reviewed Evidence
Head-to-head clinical analysis: FENTANYL 12 versus WESTADONE.
FENTANYL-12 vs WESTADONE
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Fentanyl is a synthetic opioid agonist primarily acting on mu-opioid receptors in the central nervous system, leading to analgesia, sedation, and respiratory depression.
Mu-opioid receptor agonist; also acts as an NMDA receptor antagonist and inhibits serotonin and norepinephrine reuptake.
Transdermal: 12 mcg/hour applied every 72 hours. For opioid-tolerant patients only.
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 is 3–12 hours (mean ~7 hours) in adults. Prolonged in elderly, hepatic impairment, and obesity (up to 20 hours). Context: half-life increases with continuous infusion (context-sensitive half-life).
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.
Primarily hepatic metabolism (N-dealkylation and hydroxylation) with <10% excreted unchanged in urine. Renal excretion accounts for ~75% of total elimination as metabolites; fecal excretion ~9%.
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