Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
PHENDIMETRAZINE TARTRATE vs SUPRENZA
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Phendimetrazine is a sympathomimetic amine that acts as an appetite suppressant by stimulating the hypothalamus to release norepinephrine, leading to decreased food intake and increased energy expenditure. It is a prodrug that is metabolized to phenmetrazine, which is a potent central nervous system stimulant with amphetamine-like effects.
Partial agonist at mu-opioid receptors; also a weak antagonist at kappa-opioid receptors. Provides analgesic effects with reduced respiratory depression compared to full agonists.
Management of exogenous obesity as a short-term adjunct (a few weeks) in a regimen of weight reduction based on caloric restriction,Off-label: treatment of obesity with comorbid conditions where weight loss is beneficial
Management of moderate to severe chronic pain,Off-label: Treatment of opioid use disorder (as a maintenance therapy similar to buprenorphine)
Oral: 35 mg twice daily or three times daily, 1 hour before meals; extended-release: 105 mg once daily in the morning.
Adults: 200 mg orally twice daily with meals.
Terminal half-life 3-4 hours; clinical context: requires multiple daily dosing
Terminal elimination half-life is approximately 12-15 hours in patients with normal renal function, allowing for twice-daily dosing.
Primarily metabolized in the liver via N-demethylation to its active metabolite, phenmetrazine. Other metabolites include phendimetrazine N-oxide and norphenmetrazine. CYP450 enzymes are involved, though specific isoforms not well characterized.
Primarily hepatic via CYP3A4 and CYP3A5 to norbuprenorphine (active metabolite); also undergoes glucuronidation.
Primarily renal (≥70% unchanged) with minor biliary/fecal elimination (<10%)
Approximately 60-80% of a dose is excreted renally as unchanged drug, with 20-40% eliminated via biliary/fecal routes.
10-15% bound to albumin
Approximately 95-98% bound to plasma proteins, primarily albumin.
2-3 L/kg; indicates extensive tissue distribution
Volume of distribution is approximately 2-3 L/kg, indicating extensive tissue distribution beyond plasma volume.
Oral: approximately 80-90%
Oral bioavailability is approximately 70-80%.
Contraindicated in severe renal impairment (GFR < 30 m L/min). No specific dose adjustments for mild-moderate impairment; use with caution.
e GFR <45 m L/min/1.73m²: contraindicated. e GFR ≥45: no adjustment.
Not recommended in Child-Pugh class B or C. Use with caution in mild impairment.
Child-Pugh Class A: no adjustment; Class B: reduce to 200 mg once daily; Class C: contraindicated.
Not recommended for children under 12 years; safety and efficacy not established.
Not recommended for patients under 18 years; safety and efficacy not established.
Start at lower end of dosing range; monitor for increased sensitivity and cardiovascular effects.
No specific dose adjustment; monitor renal function and use caution due to increased risk of adverse effects.
Phendimetrazine is not approved for use in patients with a history of drug abuse or dependence. It has a high potential for abuse and may lead to dependence. Use caution in patients with cardiovascular disease or hypertension.
Risk of respiratory depression, especially in non-opioid-tolerant patients. Risk of neonatal opioid withdrawal syndrome with prolonged use during pregnancy. Risk of serious injury or death due to accidental exposure in children.
Increased risk of pulmonary hypertension and valvular heart disease; monitor for dyspnea, chest pain, or edema. Tolerance may develop; discontinue if tolerance occurs. May impair ability to perform hazardous tasks. Use with caution in patients with hypertension, diabetes, or glaucoma. Do not use with MAOIs or within 14 days of discontinuation.
Respiratory depression, particularly in the first 24-72 hours of treatment; caution in patients with pulmonary disease. Risk of QT prolongation. Adrenal insufficiency. Severe hypotension. Risk of misuse, abuse, and addiction. Tolerance and physical dependence.
Hypersensitivity to phendimetrazine or any component of the formulation, advanced arteriosclerosis, symptomatic cardiovascular disease, moderate to severe hypertension, hyperthyroidism, glaucoma, agitated states, history of drug abuse, during or within 14 days of MAOI therapy
Hypersensitivity to buprenorphine or any component of the formulation. Severe respiratory insufficiency. Acute or severe bronchial asthma. Gastrointestinal obstruction, including paralytic ileus.
Avoid alcohol and excessive caffeine (coffee, tea, energy drinks) as they may increase CNS stimulation and risk of side effects. Take with or without food; high-fat meals may delay absorption of extended-release formulations. Maintain a calorie-reduced diet as part of a comprehensive weight loss plan.
No significant food interactions. Grapefruit juice may increase buprenorphine levels; avoid large quantities.
First trimester: Limited data; potential for increased risk of oral clefts. Second/third trimester: Anorexiant effects may cause fetal growth restriction; avoid use due to maternal hypertension risk.
Supr ENza (testosterone) is contraindicated in pregnancy due to virilization of female fetus. First trimester: high risk of clitoromegaly, labial fusion, and urogenital sinus abnormalities. Second and third trimesters: risk of continued virilization, including phallic enlargement and ambiguous genitalia. Fetal growth restriction may occur.
Excreted in breast milk; M/P ratio unknown. Contraindicated in breastfeeding due to potential CNS stimulation and cardiovascular effects in infant.
Testosterone is present in breast milk; M/P ratio not reported. Avoid breastfeeding due to potential for androgenization of the infant. Use only if clearly needed and no safer alternative.
Contraindicated in pregnancy; no dose adjustments recommended. Avoid use due to risks of hypertension and potential teratogenicity.
Not applicable; Supr ENza is contraindicated in pregnancy. No dose adjustments are recommended as use is avoided entirely.
Phendimetrazine tartrate is a schedule III controlled substance with high abuse potential. It is approved only for short-term (up to 12 weeks) monotherapy for exogenous obesity. Contraindicated in patients with glaucoma, hyperthyroidism, agitated states, history of drug abuse, or cardiovascular disease. Taper dose to avoid withdrawal. Monitor blood pressure and heart rate; may cause pulmonary hypertension. Avoid use with MAOIs (risk of hypertensive crisis) and within 14 days of discontinuation.
SUPRENZA (buprenorphine/naloxone) sublingual film is used for opioid dependence. Monitor for respiratory depression especially when combined with benzodiazepines or alcohol. The naloxone component is poorly absorbed sublingually but precipitates withdrawal if injected. Administer only after clear signs of withdrawal to avoid precipitated withdrawal. Adjust dose in hepatic impairment as buprenorphine is hepatically metabolized.
Take exactly as prescribed; do not increase dose or duration.,Take last dose of the day 4-6 hours before bedtime to prevent insomnia.,Do not crush or chew extended-release tablets; swallow whole.,Avoid driving or operating heavy machinery until you know how this medication affects you.,Report chest pain, shortness of breath, fainting, or leg swelling immediately.,Do not stop abruptly; follow your doctor's tapering plan.,Store securely; keep out of reach of others as this medication can be habit-forming.,Do not take with alcohol or other CNS stimulants.,Use with caution if you have high blood pressure, diabetes, or a history of depression.
Take exactly as prescribed; do not increase dose or frequency without consulting your doctor.,Place film under the tongue until fully dissolved; do not chew or swallow.,Avoid alcohol and benzodiazepines as they can cause severe respiratory depression.,Keep out of reach of children; accidental exposure can be fatal.,Do not abruptly stop; withdrawal symptoms may occur.,Store at room temperature away from moisture and heat.
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about PHENDIMETRAZINE TARTRATE vs SUPRENZA, answered by our medical review team.
PHENDIMETRAZINE TARTRATE is a Anorectic (Sympathomimetic) that works by Phendimetrazine is a sympathomimetic amine that acts as an appetite suppressant by stimulating the hypothalamus to release norepinephrine, leading to decreased food intake and increased energy expenditure. It is a prodrug that is metabolized to phenmetrazine, which is a potent central nervous system stimulant with amphetamine-like effects.. SUPRENZA is a Sympathomimetic Anorectic that works by Partial agonist at mu-opioid receptors; also a weak antagonist at kappa-opioid receptors. Provides analgesic effects with reduced respiratory depression compared to full agonists.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between PHENDIMETRAZINE TARTRATE and SUPRENZA depend on the specific clinical indication. These are agents from distinct pharmacological classes and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of PHENDIMETRAZINE TARTRATE is: Oral: 35 mg twice daily or three times daily, 1 hour before meals; extended-release: 105 mg once daily in the morning.. The standard adult dose of SUPRENZA is: Adults: 200 mg orally twice daily with meals.. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between PHENDIMETRAZINE TARTRATE and SUPRENZA in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. PHENDIMETRAZINE TARTRATE is classified as Category C. First trimester: Limited data; potential for increased risk of oral clefts. Second/third trimester: Anorexiant effects may cause fetal growth restriction; avoid use due to maternal. SUPRENZA is classified as Category C. SuprENza (testosterone) is contraindicated in pregnancy due to virilization of female fetus. First trimester: high risk of clitoromegaly, labial fusion, and urogenital sinus abnorm. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.