Phenmetrazine, sold under the brand name Preludin among others, is a stimulant drug first synthesized in 1952 and originally used as an appetite suppressant, but withdrawn from the market in the 1980s due to widespread misuse.

It was initially replaced by its analogue phendimetrazine (under the brand name Prelu-2) which functions as a prodrug to phenmetrazine, but now it is rarely prescribed, due to concerns of misuse and addiction.

[2] Phenmetrazine has been found to produce similar weight loss to dextroamphetamine in people with obesity.

[4][5][2] Phenmetrazine has been shown to produce very similar subjective psychostimulant effects to those of amphetamine and methamphetamine in clinical studies.

[4][5] Although able to produce comparable effects however, phenmetrazine has only about one-fifth to one-third of the potency of dextroamphetamine by weight.

[21] Dopamine-releasing drugs that lack VMAT2 activity are theorized to produce much smaller maximal impacts on dopamine levels under experimental conditions than those which also act on VMAT2 like amphetamine.

Both of these dosage forms share a similar bioavailability as well as time to peak onset, however, sustained-release formulations offer improved pharmacokinetics with a steady release of active ingredient which results in a lower peak concentration in blood plasma.

The molecule also loosely resembles ethcathinone, the active metabolite of popular anorectic amfepramone (diethylpropion).

[31] Phenmetrazine is the generic name of the drug and its INNTooltip International Nonproprietary Name, USANTooltip United States Adopted Name, and BANTooltip British Approved Name.

[35] 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.

At first, Preludin tablets were smuggled, but soon the smugglers started bringing in raw phenmetrazine powder.

The Beatles had to play for hours, and they were often given the drug (referred to as "prellies") by the maid who cleaned their housing arrangements, German customers, or by Astrid Kirchherr (whose mother bought them).

[36] Hunter Davies asserted, in his 1968 biography of the band,[37] that their use of such stimulants then was in response to their need to stay awake and keep working, rather than a simple desire for kicks.