Adipex-P is the brand name under which phentermine hydrochloride is sold by Gates Pharmaceuticals, a subsidiary of Teva Pharmaceuticals. First approved almost half a century ago in 1959 as an appetite suppressant, phentermine is also sold under the brand name Ionamin as well as under its generic name.

Adipex-P is a sympathomimetic amine, which is similar to an amphetamine. It is also known as an "anorectic" or "anorexigenic" drug. It stimulates the central nervous system (nerves and brain), which increases your heart rate and blood pressure, and it suppresses your appetite.

During the 1990s, phentermine was commonly used with another medication called Fenfluramine hydrochloride in a combination referred to as Fen-phen. In 1997, this combination became the center of a storm, and fenfluramine and dexfenfluramine were taken off the market for possibly causing heart valve damage.

Because of possible adverse effects and contraindications for use, Adipex-P is generally used to treat obesity only for a brief period of time. It is recommended only for people with an initial body mass index (BMI) of 30 or greater (27 or greater if the person has other risk factors).

WARNINGS:

Adipex-P is indicated only as short-term monotherapy for the management of exogenous obesity. The safety and efficacy of combination therapy with phentermine and any other drug products for weight loss, including selective serotonin reuptake inhibitors (e.g., fluoxetine, sertraline, fluvoxamine, paroxetine), have not been established. Therefore, coadministration of these drug products for weight loss is not recommended.

Primary Pulmonary Hypertension (PPH) - a rare, frequently fatal disease of the lungs - has been reported to occur in patients receiving a combination of phentermine with fenfluramine or dexfenfluramine. The possibility of an association between PPH and the use of phentermine alone cannot be ruled out; there have been rare cases of PPH in patients who reportedly have
taken phentermine alone.

The initial symptom of PPH is usually dyspnea. Other initial symptoms include: angina pectoris, syncope or lower extremity edema. Patients should be advised to report immediately any deterioration in exercise tolerance. Treatment should be discontinued in patients who develop new, unexplained symptoms of dyspnea, angina pectoris, syncope or lower extremity edema.

Valvular Heart Disease: Serious regurgitant cardiac valvular disease, primarily affecting the mitral, aortic and/or tricuspid valves, has been reported in otherwise healthy persons who had taken a combination of phentermine with fenfluramine or dexfenfluramine for weight loss. The etiology of these valvulopathies has not been established and their course in individuals after the drugs are stopped is not known. The possibility of an association between
valvular heart disease and the use of phentermine alone cannot be ruled out; there have been rare cases of valvular heart disease in patients who reportedly have taken phentermine alone.

Tolerance to the anorectic effect usually develops within a few weeks. When this occurs, the recommended dose should not be exceeded in an attempt to increase the effect; rather, the drug should be discontinued.

Adipex-P may impair the ability of the patient to engage in potentially hazardous activities such as operating machinery or driving a motor vehicle; the patient should therefore be cautioned accordingly.

DRUG ABUSE AND DEPENDENCE:

Adipex-P is related chemically and pharmacologically to the amphetamines. Amphetamines and related stimulant drugs have been extensively abused, and the possibility of abuse of Adipex-P should be kept in mind when evaluating the desirability of including a drug as part of a weight reduction program. Abuse of amphetamines and related drugs may be associated with intense psychological dependence and severe social dysfunction. There are reports of patients who have increased the dosage to many times that recommended.

Abrupt cessation following prolonged high dosage administration results in extreme fatigue and mental depression; changes are also noted on the sleep
EEG. Manifestations of chronic intoxication with anorectic drugs include severe dermatoses, marked insomnia, irritability, hyperactivity and personality changes. The most severe manifestation of chronic intoxications is psychosis, often clinically indistinguishable from schizophrenia.

Usage with Alcohol: Concomitant use of alcohol with Adipex-P may result in an adverse drug interaction.

PRECAUTIONS:

General
Caution is to be exercised in prescribing Adipex-P (phentermine hydrochloride) for patients with even mild hypertension. Insulin requirements in diabetes mellitus may be altered in association with the use of Adipex-P and the concomitant dietary regimen. Adipex-P may decrease the hypotensive effect of guanethidine.

The least amount feasible should be prescribed or dispensed at one time in order to minimize the possibility of overdosage.