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

While the addition of an N-methyl group to amphetamine significantly increases its potency and bioavailability, methylation of phenmetrazine renders the compound virtually inactive.

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.

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.