Phentermine is an appetite suppressant of the amphetamine
and phenethylamine class.
It is approved as an appetite suppressant to help reduce
weight in obese patients when used short-term and combined with exercise,
diet, and behavioral modification. It is typically prescribed for
individuals who are at increased medical risk because of their weight
and works by helping to release certain chemicals in the brain that
control appetite.
In 1959 phentermine first received approval from the
FDA as an appetite suppressing drug. Phentermine hydrochloride then
became available in the early 1970s. It was previously sold as Fastin
from King Pharmaceuticals for SmithKline Beecham, however in 1998
it was removed from the market. Medeva Pharmaceuticals sells the name
brand of phentermine called Ionamin® and Gate Pharmaceuticals
sells it as Adipex-P. Phentermine is also currently sold as a generic.
Since the drug was approved in 1959 there have been almost no clinical
studies performed. The most recent study was in 1990 which combined
phentermine with fenfluramine or dexfenfluramine and became known
as Fen-Phen.
A study was published in 1992 that Fen-Phen was more
effective than diet and exercise with few side effects. However, in
1997 after 24 cases of heart valve disease in Fen-Phen users, fenfluramine
and dexfenfluramine were voluntarily taken off the market at the request
of the FDA. Studies later proved that nearly 30% of people taking
fenfluramine or dexfenfluramine had abnormal valve findings. The FDA
did not ask manufacturers to remove phentermine from the market.
Phentermine is still available by itself in most countries,
including the U.S. However, because it is similar to amphetamines,
individuals may develop an addiction to it. Hence, it is classified
as a controlled substance in many countries. Internationally, phentermine
is a schedule IV drug under the Convention on Psychotropic Substances.[1]
In the United States, it is classified as a Schedule IV controlled
substance under the Controlled Substances Act.
