Of the many available weight loss drugs from which to choose, Bontril is one of the most popular. The active chemical in Bontril (its trade name) is phendimetrazine – a chemical relative of amphetamines, an illegal drug known to speed up the metabolism and cause dramatically fast weight loss. Phendimetrazine is available on prescription and is regarded as a 'controlled substance' under United States law.

The chemical is found in products such as Bontril in the form of phendimetrazine tartrate, and is known to be incredibly effective. Once administered, a third of the drug is metabolized by the body and reformed as phenmetrazine. It is known that the greater the proportion of the phendimetrazine which is converted into phenmetrazine, the more likely the individual is to become chemically dependent upon the drug.

The problem of chemical dependence is a serious one, and for this reason long-term use of Bontril is not recommended by doctors. Its effectiveness – and the speed at which the drug works – does, however, make it incredibly useful for those who are dangerously overweight and at imminent risk of some lethal disease as a result of their weight.