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Phenmetrazine chemical structure

IUPAC name
CAS number
ATC code


Chemical formula {{{chemical_formula}}}
Molecular weight 177.2456
Elimination half-life 8 hours
Excretion Renal
Pregnancy category
Legal status
Routes of administration Oral, Intravenous, Vaporized, Insufflated, Suppository

Phenmetrazine is a stimulant of the central nervous system. It was previously sold under the trade name Preludin as an anorectic. Preludin has since been removed from the market. It was initially replaced by the weaker analogue Phendimetrazine (Bontril), but this is now only rarely prescribed, due to problems with abuse.

Other names that have been used for Phenmetrazine include: Defenmetrazin, Fenmetrazin, Oxazimedrine, Phenmetraline.


It was first patented in Germany in 1952 by Boehringer-Ingelheim. It was the result of a search by Thomae and Wick for an anorectic substance without the side-effects of amphetamine[1] . Phenmetrazine was introduced into clinical use in 1954 in Europe[2] .

Medical use

In clinical use phenmetrazine produces less nervousness, hyperexcitability, euphoria and insomnia than the amphetamines[3]. It doesn't tend to increase the pulse either[1]. Due to the relative lack of side-effects, one study found it well tolerated in children[1]. In a study of the effectiveness on weight loss between phenmetrazine and dextroamphetamine, phenmetrazine was found to be slightly more efficient[4].

Even though the manufacturers claimed it had "exceptional safety and strikingly low incidence of side effects", within some years there were some reports of psychotic reactions of the amphetamine type[2].

After an oral dose, about 70% of the drug is excreted from the body within 24 hours. About 19% of that is excreted as the unmetabolised drug and the rest as various metabolites[5]

In trials in rats it has been found that after subcutaneous administration, both the optical isomers of phenmetrazine is equally effective in reducing food intake, but in oral administration the levo isomer is more effective. In terms of central stimulation however, the dextro isomer is about 4 times as effective in both methods of administration[6].


It is by some considered to have a greater potential for addiction than the amphetamines, and has been abused in many countries, for example Sweden. When stimulant abuse first became prevalent in Sweden in the 1950s, phenmetrazine was preferred to amphetamine and methamphetamine by addicts, as it was considered the superior drug. In the autobiographical novel "Rush" by Kim Wozencraft, intravenous phenmetrazine is described as the most euphoric and pro-sexual of the stimulants the author used.

Phenmetrazine was classified as a narcotic in Sweden in 1959, and was taken completely off the market in 1965. At first the illegal demand was satisfied by smuggling from Germany and later Spain and Italy. At first Preludin tablets was smuggled, but after a while the smugglers started bringing in raw phenmetrazine powder. Eventually Amphetamine became the dominant stimulant of abuse because of its easier availability.


  1. 1.0 1.1 1.2 Martel, Antonio (1957). Preludin (Phenmetrazine) in the Treatment of Obesity. Can. Med. Assoc. J. 76: 117.
  2. 2.0 2.1 Kalant, Oriana Josseau (1966). The Amphetamines: Toxicity and Addiction.
  3. (1957). Phenmetrazine Hydrochloride. J. Am. Med. Assoc. 163 (5): 357.
  4. Hampson, J (1960). Phenmetrazine and Dexamphetamine in the Management of Obesity. The Lancet 275 (7137): 1265.
  5. Anthony C Moffat, M David Osselton and Brian Widdop. Clarke's Analysis of Drugs and Poisons.
  6. Engelhardt, A (1961). Studies of the Mechanism of the Anti-Appetite Action of Phenmetrazine. Biochem. Pharmacol. 8 (1): 100.
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