Comparative Pharmacology
Head-to-head clinical analysis: FENTANYL CITRATE versus WESTADONE.
Peer-Reviewed Evidence
Head-to-head clinical analysis: FENTANYL CITRATE versus WESTADONE.
FENTANYL CITRATE vs WESTADONE
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Fentanyl is a potent synthetic opioid agonist that primarily acts on mu-opioid receptors in the central nervous system, leading to analgesia, sedation, and euphoria. It also interacts with kappa and delta opioid receptors to a lesser extent. By binding to these receptors, fentanyl inhibits adenylate cyclase, reduces cAMP production, closes voltage-gated calcium channels, and opens inwardly rectifying potassium channels, resulting in hyperpolarization and reduced neurotransmitter release.
Mu-opioid receptor agonist; also acts as an NMDA receptor antagonist and inhibits serotonin and norepinephrine reuptake.
Initial adult dose 50-100 mcg IV/IM every 1-2 hours as needed for pain; for anesthesia induction 2-20 mcg/kg IV.
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 4-6 hours in adults). Context: Prolonged with hepatic impairment, elderly, or continuous infusion (context-sensitive half-life increases with infusion duration).
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 to norfentanyl and other metabolites); less than 10% excreted unchanged in urine; approximately 9% excreted in feces via biliary elimination.
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