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Trade namesBontril, Adipost, Anorex-SR, others
  • 3,4-dimethyl-2-phenylmorpholine
Clinical data
Drug classAmphetamine[1]
Main usesObesity[1]
Side effectsPalpitations, fast heart rate, high blood pressure, agitation, trouble sleeping, headache, psychosis, diarrhea[1]
  • C (US)
Routes of
By mouth
External links
Legal status
BioavailabilityPeak plasma levels occur within 1 to 3 hours. Absorption is usually complete by 4 to 6 hours
Elimination half-life19-24 hours
ExcretionUrinary elimination
Chemical and physical data
Molar mass191.274 g·mol−1
3D model (JSmol)
  • O2C(c1ccccc1)C(N(C)CC2)C
  • InChI=1S/C12H17NO/c1-10-12(14-9-8-13(10)2)11-6-4-3-5-7-11/h3-7,10,12H,8-9H2,1-2H3 checkY

Phendimetrazine, sold under the brand name Bontril among others, is a medication used to treat obesity.[1] Use is only recommended for a few weeks.[1] It is used together with dieting and exercise.[1][2] It is taken by mouth.[1]

Common side effects include palpitations, fast heart rate, high blood pressure, agitation, trouble sleeping, headache, psychosis, and diarrhea.[1] Other side effects may include abuse, valvular heart disease, and pulmonary hypertension.[1] Use during pregnancy may harm the baby.[3] It is an amphetamine which works by decreasing appetite.[1]

Phendimetrazine was approved for medical use in the United States in 1975.[1] Europe voted to removal approval in 1999.[4] It is available as a generic medication.[2] In the United States 60 tablets of 35 mg costs about 10 USD as of 2021.[2] In the United States it is a Schedule III controlled substance.[5]

Medical uses


For obesity in adults, it is taken at a dose of 35 mg immediate release two to three times per day.[1] A long acting formulation may be taken as 105 mg once per day.[1]


It is a stimulant drug of the morpholine chemical class used as an appetite suppressant.[6]

Phendimetrazine functions as a prodrug to phenmetrazine; approximately 30 percent of an oral dose is converted into it. Phendimetrazine can essentially be thought of as an extended-release formulation of phenmetrazine with less potential for abuse. Phendimetrazine is an anorectic drug which acts as a norepinephrine-dopamine releasing agent (NDRA).[7]

As an amphetamine congener, its structure incorporates the backbone of methamphetamine, a potent CNS stimulant. While the addition of an N-methyl group to amphetamine significantly increases its potency and bioavailability, methylation of phenmetrazine renders the compound virtually inactive. However, phendimetrazine is a prodrug for phenmetrazine which acts as the active metabolite. Phendimetrazine possesses preferable pharmacokinetics over phenmetrazine as a therapeutic agent because its metabolization by demethylases produces a more steady and prolonged exposure of active drug within the body. This decreases abuse potential as the peak blood-concentration of active phenmetrazine that's produced from a single dose of phendimetrazine is lower than a single therapeutically equivalent dose of phenmetrazine.

Indicated as a short-term secondary treatment for exogenous obesity, phendimetrazine immediate-release 35mg tablets are typically consumed one hour before meals, not to exceed three doses daily. Phendimetrazine is also manufactured as a 105mg extended-release capsule for once daily dosing, typically consumed 30 to 60 minutes before a morning meal. Whereas the immediate-release formulation has a maximum daily dosage of 210mg (6 tablets), the extended-release capsules have a maximum daily dosage of 105mg (one capsule).

Society and culture


Adipost, Anorex-SR, Appecon, Melfiat, Obezine, Phendiet, Plegine, Prelu-2, Statobex


According to the List of Psychotropic Substances under International Control Archived 2020-05-10 at the Wayback Machine published by the International Narcotics Control Board, phendimetrazine is a Schedule III controlled substance under the Convention on Psychotropic Substances.[8]


  1. 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 "Phendimetrazine Monograph for Professionals". Archived from the original on 27 January 2021. Retrieved 27 October 2021.
  2. 2.0 2.1 2.2 "Phendimetrazine Prices, Coupons & Savings Tips - GoodRx". GoodRx. Archived from the original on 6 February 2017. Retrieved 27 October 2021.
  3. "Phendimetrazine Use During Pregnancy". Archived from the original on 5 December 2020. Retrieved 27 October 2021.
  4. "" (PDF). Archived (PDF) from the original on 28 October 2021. Retrieved 27 October 2021. {{cite web}}: External link in |title= (help)
  5. "PART 1308 - Section 1308.13 Schedule III". Archived from the original on 18 October 2021. Retrieved 27 October 2021.
  6. Landau D, Jackson J, Gonzalez G (2008). "A case of demand ischemia from phendimetrazine". Cases J. 1 (1): 105. doi:10.1186/1757-1626-1-105. PMC 2531092. PMID 18710555. Archived from the original on 2014-10-23. Retrieved 2020-09-26.
  7. Rothman RB, Baumann MH (2006). "Therapeutic potential of monoamine transporter substrates". Current Topics in Medicinal Chemistry. 6 (17): 1845–59. doi:10.2174/156802606778249766. PMID 17017961. Archived from the original on 2017-03-26. Retrieved 2020-05-05.
  8. "List of psychotropic substances under international control" (PDF). Archived from the original (PDF) on 2012-08-31. Retrieved 2020-09-26.

External links