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“Mephenmetrazine” redirects here. For other methyl substitutions of phenmetrazine, see Phenmetrazine § Substituted phenmetrazines.

Phendimetrazine, sold under the brand name Bontril among others, is a stimulant medication of the morpholine chemical class used as an appetite suppressant.[2]

Pharmacology

Phendimetrazine tablets and capsules

Phendimetrazine functions as a prodrug of 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).[3]

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.[4] 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).

Legality

According to the List of Psychotropic Substances under International Control published by the International Narcotics Control Board, phendimetrazine is a Schedule III controlled substance under the Convention on Psychotropic Substances.[5]

Synthesis

The reaction between N-methylethanolamine and 2-bromopropiophenone gives compound (3), which is reductively cyclized using formic acid to synthesize phendimetrazine.[6][7]

Society and culture

Brand names

It is sold under various brand names including Bontril, Bontril PDM, Adipost, Anorex-SR, Appecon, Melfiat, Obezine, Phendiet, Plegine, Prelu-2, and Statobex.[8][9]

References

  1. ^ Anvisa (31 March 2023). “RDC Nº 784 – Listas de Substâncias Entorpecentes, Psicotrópicas, Precursoras e Outras sob Controle Especial” [Collegiate Board Resolution No. 784 – Lists of Narcotic, Psychotropic, Precursor, and Other Substances under Special Control] (in Brazilian Portuguese). Diário Oficial da União (published 4 April 2023). Archived from the original on 3 August 2023. Retrieved 16 August 2023.
  2. ^ 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.
  3. ^ 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. Retrieved 5 May 2020.
  4. ^ Banks ML, Blough BE, Fennell TR, Snyder RW, Negus SS (June 2013). “Role of phenmetrazine as an active metabolite of phendimetrazine: evidence from studies of drug discrimination and pharmacokinetics in rhesus monkeys”. Drug and Alcohol Dependence. 130 (1–3): 158–166. doi:10.1016/j.drugalcdep.2012.10.026. PMC 3616150. PMID 23211394.
  5. ^ “List of psychotropic substances under international control” (PDF). Archived from the original (PDF) on 31 August 2012. Retrieved 15 June 2005.
  6. ^ “Phendimetrazine”. Thieme. Archived from the original on 26 October 2023. Retrieved 30 June 2024.
  7. ^ Werner Heel and Karl Zeile, U.S. patent 2,997,469 (1961 to Ingelheim, Germany, assignors to C. H. Boehringer Sohn, Ingelheim, Germany, a partnership).
  8. ^ “Phendimetrazine Tartrate (Phendimetrazine Tartrate): Side Effects, Uses, Dosage, Interactions, Warnings”. RxList. Retrieved 23 May 2025.
  9. ^ “Phendimetrazine (oral route)”. Mayo Clinic. Retrieved 29 June 2025.