Medications and Drugs
Pharmacy Author: Omudhome Ogbru, PharmD
Medical and Pharmacy Editor: Jay W. Marks, MD
GENERIC NAME: phentermine
BRAND NAMES: Adipex-P, Obenix, Oby-Trim
DRUG CLASS AND MECHANISM: Phentermine is a drug that suppresses appetite. Its exact
mechanism of action is unknown. It probably decreases appetite by acting on
centers in the brain that control appetite. Phentermine is similar to
amphetamine. It stimulates the nervous system, elevates blood pressure, and
increases heart rate.
PRESCRIPTION: Yes
GENERIC AVAILABLE: Yes
PREPARATIONS: Tablets: 30 and 37.5mg.
STORAGE: Phentermine should be stored in a tight container at room
temperature.
PRESCRIBED FOR: Phentermine is combined with
diet and
exercise for the
short-term treatment of obesity in individuals with a
body mass index greater
than or equal to 30 kg/m2 or greater than or equal to 27 kg/m2 with risk factors
for heart disease. Phentermine should not be combined with other weight loss
agents. The combination of phentermine and fenfluramine (FEN-PHEN) is associated
with serious heart problems. Fenfluramine is no longer available in the United
States.
DOSING: The recommended dose is 30 mg once daily about 2 hours after
breakfast. Evening doses should be avoided because phentermine causes insomnia.
DRUG INTERACTIONS: Phentermine is similar to amphetamine and may share some
of the interactions associated with amphetamines. Combining phentermine with
tricyclic antidepressants [for example, amitriptyline
(Elavil, Endep)] or monoamine oxidase inhibitors
(for example, tranylcypromine) may result in high blood pressure and other serious
reactions because of elevated serotonin levels in the blood.
PREGNANCY: Use of phentermine during
pregnancy has not been adequately
evaluated.
NURSING MOTHERS: It is not known whether phentermine is excreted in
human
breast milk.
SIDE EFFECTS: Side effects of phentermine include
nausea,
vomiting, diarrhea,
dry mouth, constipation, an unpleasant taste, hives,
impotence, palpitations,
high blood pressure, and fast heart rates (palpitations). Central nervous system
side effects include hyperactivity, insomnia, restlessness, tremor, and
dizziness. Phentermine, especially when combined with fenfluramine, has been
associated with high pressures in the pulmonary arteries (pulmonary
hypertension) and defects in heart valves, both serious complications. Physical
and psychological dependence may occur with the long-term use of phentermine. A
withdrawal reaction, which includes excessive drowsiness, fatigue, tremors and
depression may occur after prolonged use.
Reference: FDA Prescribing Information
Last Editorial Review: 8/28/2007
Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.
- Drug Interactions - Learn about potential drug interactions you may be exposed to. Drug interactions can occur with prescription drugs, OTC medication, vitamins, herbs, and supplements.
- Obesity - Learn about obesity and being overweight including the health risks, causes, review of weight loss diet plans, surgical and non-surgical treatments, and medications to treat the disease.
- Drugs: What You Should Know About Your Drugs - Find out what you should know about your drugs such as side effects, warnings and precautions, storage information, and if a generic version is as good as the brand name.
Latest Medical News
Back to Medications Index
Diet & Weight Management RSS