Comparative Pharmacology
Head-to-head clinical analysis: ADIPEX P versus FENFLURAMINE.
Peer-Reviewed Evidence
Head-to-head clinical analysis: ADIPEX P versus FENFLURAMINE.
ADIPEX-P vs FENFLURAMINE
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Phentermine is a sympathomimetic amine that stimulates release of norepinephrine and to a lesser extent dopamine and serotonin from presynaptic nerve terminals in the hypothalamic feeding center, resulting in appetite suppression.
Fenfluramine is a serotonin-releasing agent and serotonin receptor agonist. It increases extracellular serotonin levels by promoting release from presynaptic neurons and inhibiting reuptake, leading to appetite suppression. Its antiseizure effect in Dravet syndrome is thought to be mediated via 5-HT2 receptor activation, enhancing inhibitory neurotransmission.
Phentermine (ADIPEX-P) is typically dosed as 15–37.5 mg orally once daily, administered 2 hours after breakfast or before breakfast. The 37.5 mg tablet is taken once daily before breakfast or 1–2 hours after breakfast; some patients may require 15 mg or 30 mg (half of a 37.5 mg tablet) once daily. The extended-release formulation (ADIPEX-P) is not available; only immediate-release tablets are marketed. Duration of therapy should be limited to a few weeks (e.g., 4–12 weeks) due to potential for tolerance and abuse.
25 mg orally three times daily, titrated to a maximum of 400 mg daily in divided doses.
None Documented
Clinical Note
moderateDexfenfluramine + Deferasirox
"The serum concentration of Deferasirox can be increased when it is combined with Dexfenfluramine."
Clinical Note
moderateDexfenfluramine + Haloperidol
"The metabolism of Haloperidol can be decreased when combined with Dexfenfluramine."
Clinical Note
moderateDexfenfluramine + Tenofovir disoproxil
"The metabolism of Tenofovir disoproxil can be decreased when combined with Dexfenfluramine."
Clinical Note
moderateDexfenfluramine + Artesunate
None Documented
Terminal half-life approximately 20-25 hours. Clinical context: Steady-state reached within 4-5 days; dosing adjustments may be needed in renal impairment.
Terminal elimination half-life of fenfluramine is approximately 20 hours (range 13–30 hours) for the parent drug, while its active metabolite norfenfluramine has a longer half-life of approximately 30–34 hours. This extended half-life supports twice-daily dosing but contributes to accumulation with repeated administration.
Primarily renal (70-90% unchanged); minor biliary/fecal (10-30% as metabolites). Urinary pH-dependent; acidic urine increases excretion.
Renal excretion of unchanged drug accounts for <1% of the administered dose; fenfluramine is extensively metabolized, with metabolites primarily excreted renally. Approximately 60–70% of the dose appears in urine as metabolites (including norfenfluramine and other dealkylated products) within 72 hours, and about 5–10% is eliminated in feces via biliary excretion.
Category C
Category C
Anorexiant
Anorexiant
"The serum concentration of the active metabolites of Artesunate can be reduced when Artesunate is used in combination with Dexfenfluramine resulting in a loss in efficacy."