Phentermine Hydrochloride (12 brand names, 4 dosage forms, 1 route)
Available dosage forms: CAPSULE, TABLET, CAPSULE, EXTENDED RELEASE, TABLET, ORALLY DISINTEGRATING.
Routes of administration: ORAL.
Brand Names
- ADIPEX-P
- FASTIN
- LOMAIRA
- OBESTIN-30
- OBY-TRIM
- ONA-MAST
- PHENTERMINE HYDROCHLORIDE
- PHENTERMINE HYDROCHLORIDE AND TOPIRAMATE
- QSYMIA
- SUPRENZA
- TORA
- WILPO
Indications and Usage
Phentermine hydrochloride tablets are indicated as a short-term (a few weeks) adjunct in a regimen of weight reduction based on exercise, behavioral modification and caloric restriction in the management of exogenous obesity for patients with an initial body mass index greater than or equal to 30 kg/m2, or greater than or equal to 27 kg/m2 in the presence of other risk factors (e.g., controlled hypertension, diabetes, hyperlipidemia). Below is a chart of body mass index (BMI) based on various heights and weights. BMI is calculated by taking the patient’s weight, in kilograms (kg), divided by the patient’s height, in meters (m), squared. Metric conversions are as follows: pounds ÷ 2.2 = kg; inches x 0.0254 = meters. BODY MASS INDEX (BMI), kg/m2 Height (feet, inches) Weight (pounds) 5’0” 5’3” 5’6” 5’9” 6’0” 6’3” 140 27 25 23 21 19 18 150 29 27 24 22 20 19 160 31 28 26 24 22 20 170 33 30 28 25 23 21 180 35 32 29 27 25 23 190 37 34 31 28 26 24 200 39 36 32 30 27 25 210 41 37 34 31 29 26 220 43 39 36 33 30 28 230 45 41 37 34 31 29 240 47 43 39 36 33 30 250 49 44 40 37 34 31 The limited usefulness of agents of this class, including phentermine, [see Clinical Pharmacology (12.1, 12.2) ] should be measured against possible risk factors inherent in their use such as those described below.
Contraindications
History of cardiovascular disease (e.g., coronary artery disease, stroke, arrhythmias, congestive heart failure, uncontrolled hypertension) During or within 14 days following the administration of monoamine oxidase inhibitors Hyperthyroidism Glaucoma Agitated states History of drug abuse Pregnancy [see Use in Specific Populations (8.1) ] Nursing [see Use in Specific Populations (8.3) ] Known hypersensitivity, or idiosyncrasy to the sympathomimetic amines
Adverse Reactions
The following adverse reactions are described, or described in greater detail, in other sections: - Primary pulmonary hypertension [see Warnings and Precautions (5.2) ] - Valvular heart disease [see Warnings and Precautions (5.3) ] - Effect on the ability to engage in potentially hazardous tasks [see Warnings and Precautions (5.5) ] - Withdrawal effects following prolonged high dosage administration [see Drug Abuse and Dependence (9.3) ] The following adverse reactions to phentermine have been identified: Cardiovascular Primary pulmonary hypertension and/or regurgitant cardiac valvular disease, palpitation, tachycardia, elevation of blood pressure, ischemic events. Central Nervous System Overstimulation, restlessness, dizziness, insomnia, euphoria, dysphoria, tremor, headache, psychosis. Gastrointestinal Dryness of the mouth, unpleasant taste, diarrhea, constipation, other gastrointestinal disturbances. Allergic Urticaria. Endocrine Impotence, changes in libido.
Mechanism of Action
Phentermine is a sympathomimetic amine with pharmacologic activity similar to the prototype drugs of this class used in obesity, amphetamine (d- and d/l-amphetamine). Drugs of this class used in obesity are commonly known as “anorectics” or “anorexigenics.” It has not been established that the primary action of such drugs in treating obesity is one of appetite suppression since other central nervous system actions, or metabolic effects, may also be involved.
Overdosage
The least amount feasible should be prescribed or dispensed at one time in order to minimize the possibility of overdosage.