Phentermine is controlled substance and an appetite suppressant weight loss medication or diet pill that has been on the market for over 50 years in the United States. Approved by the US FDA in 1959, Phentermine has been on the market for a long time with proven safety record. Phentermine is used for a limited period of time to speed weight loss in overweight people who are exercising and eating a low-calorie diet. Phentermine is in a class of medications called anorectics. It works by decreasing appetite. Phentermine comes as tablets and extended-release capsules. It usually is taken as a single daily dose in the morning or three times a day 30 minutes before meals.
Indications for Phentermine
ADIPEX-P® is a sympathomimetic amine anorectic weight loss medication indicated as a short-term adjunct in a regimen of weight decrease based on exercise, behavioral modification and caloric limit in the management of exogenous obesity for patients with:
- a primary body mass index ≥ 30 kg/m2, or
- ≥ 27 kg/m2 along with other risk factors such as controlled hypertension, metabolic syndrome, diabetes, hyperlipidemia etc.
Adverse effects of Phentermine
Phentermine is generally well tolerated and most people may not experience any major side effects.
Treatment should be discontinued inpatients who develop new, unexplained symptoms of dyspnea, angina pectoris, syncope or smaller extremity edema, and patients should be evaluated for the possible occurrence of pulmonary hypertension.
Common (1% or more in incidence) adverse effects include:
- Xerostomia (dry mouth)
- Urinary frequency
- Facial oedema
- Unpleasant taste
- Changes in libido
Rare (1% or less incidence) adverse effects include:
- Primary pulmonary hypertension
- Valvular heart disease (in combination with dexfenfluramine and fenfluramine; causal relationship unclear)
- Increased seizure activity in people with epilepsy
- Withdrawal symptoms on stopping
- Ischaemic events
Weight loss medications
In 2012, the FDA approved two new weight loss medications Qsymia and Belviq after years of rejecting many other weight loss medications. There are other traditional and time tested weight loss medications such as Phentermine, Phendimetrazine etc.
What works and what does not for losing weight?
Cautions and interactions
Phentermine use is contraindicated in those who are: Known hypersensitivity or idiosyncratic reaction to sympathomimetic amines Taking amphetamine (i.e., Adderall, Dexedrine, Vyvanse), dexfenfluramine, fenfluramine, furazolidone, guanadrel, guanethidine, or have taken a monoamine oxidase inhibitor (MAOI) (e.g., phenelzine) in the last 14 days Hyperthyroidism Glaucoma Peptic ulcer Prostatic hypertrophy Epilepsy Simultaneous treatment with drugs that increase blood pressure Contraindicated in cardiac disease (e.g. advanced arteriosclerosis, pulmonary hypertension, uncontrolled hypertension, arrhythmias) and cerebrovascular disease (stroke) Pregnant, planning to become pregnant, or are breast-feeding Those receiving serotonergic medications such as the selective serotonin reuptake inhibitors, serotonin-norepinephrine reuptake inhibitor, tricyclic antidepressant, due to the potential for serotonin syndrome to be precipitated by the treatment.
Mechanism of action
It is believed to suppress the appetite and increases the metabolism by its actions on the appetite center
Dosing and administration
It is available in 15 mg, 30 mg and 37.5 mg in tablet and capsule form.
Brand names available
- Adipex P (immediate release)
- Ionamin (slow-release resin, Australia, discontinued in the US)
- Pro-Fast SA
- Qsymia (with topiramate)
- Phentermine Trenker
- Suprenza (disintegrates orally)
Phentermine and Topiramate
Phentermine is often combined with Topiramate like in the brand name Qsymia for better weight loss results, mitigate some of the side effects, and increase effectiveness. In fact, in a large 30,000 patient diet pill comparison study published in JAMA that compared new prescription weight loss medications or diet pills, Qsymia was considered the most effective weight loss prescription medication.