• Obesity

Benzphetamine Generic Name & Formulations

General Description

Benzphetamine HCl 50mg; scored tabs.

Pharmacological Class


How Supplied

Contact supplier


Store at 20° to 25°C with excursions permitted between 15° to 30°C (59° to 86°F).

Benzphetamine Indications


Management of exogenous obesity as a short term (a few weeks) adjunct in a regimen of weight reduction based on caloric restriction in patients with an initial body mass index (BMI) of 30 kg/m2 or higher who have not responded to appropriate weight reducing regimen (diet and/or exercise) alone.

Benzphetamine Dosage and Administration

Prior to Treatment Evaluations

Baseline cardiac evaluation should be considered to detect pre-existing valvular heart diseases or pulmonary hypertension prior to initiation of benzphetamine treatment.


≥17yrs: Individualized. Initially 25–50mg once daily in mid-morning or mid-afternoon. Increase if needed to 25–50mg 1–3 times daily. Continue treatment only if patient has satisfactory weight loss within the first 4 weeks of treatment (eg, weight loss of at least 4lbs, or as determined by the physician and patient).


<17yrs: not recommended.

Benzphetamine Contraindications


Advanced arteriosclerosis. Cardiovascular disease. Hypertension. Hyperthyroidism. Agitation. Drug or alcohol abuse. During or within 14 days of MAOIs. Pregnancy.

Benzphetamine Boxed Warnings

Not Applicable

Benzphetamine Warnings/Precautions


See Contraindications. Risk of pulmonary hypertension, valvular heart disease. Discontinue if new, unexplained dyspnea, angina, syncope, or lower extremity edema develops. Discontinue if tolerance to the anorectant effect develops. Mild hypertension. Diabetes. Prescribe minimal supply to avoid overdose.  Elderly.


Pulmonary Hypertension (PH)

  • In a case-control epidemiological study, the use of anorectic agents was associated with an increased risk of developing pulmonary hypertension; benzphetamine was not specifically studied in this case-control study.
  • Treatment should be discontinued if patients report symptoms of PH (eg, unexplained dyspnea, angina, syncope, lower extremity pain); evaluate for possible pulmonary hypertension.
  • Baseline evaluation should be considered to detect pre-existing pulmonary hypertension.

Valvular Heart Disease

  • Cardiac valvular disease has been reported in patients taking anoretic agents such as fenfluramine or dexfenfluramine.
  • No cases of this valvulopathy have been reported when benzphetamine has been used alone.
  • Baseline cardiac evaluation should be considered to detect pre-existing valvular heart diseases.
  • Not recommended in patients with known heart murmur or valvular heart disease.

Development of Tolerance

  • Recommended dose should not be exceeded in an attempt to increase the effect.
  • Discontinue benzphetamine if tolerance develops.

Risk of Dependence

  • Consider abuse potential when evaluating the desirability of including the drug as part of a weight reduction program.


  • Not recommended for severely hypertensive patients or for patients with symptomatic cardiovascular disease including arrhythmias.
  • Use caution in patients with mild hypertension.

Pregnancy Considerations

Benzphetamine is contraindicated in pregnancy.

Nursing Mother Considerations

Amphetamines are excreted in human milk. Mothers taking amphetamines should be advised to refrain from nursing.

Pediatric Considerations

Safety and effectiveness in pediatric patients have not been established. The use of benzphetamine is not recommended in patients less than 17 years of age.

Geriatric Considerations

In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range. Studies did not include a sufficient number of patients aged 65 years and older.

Benzphetamine Pharmacokinetics




Renal. Half-life: 4–5 hours.

Benzphetamine Interactions


Contraindicated with MAOIs as hypertensive crisis may result. Should not be used in combination with other anorectic agents; potential for serious cardiac problems. Adverse interactions with alcohol should be considered. Do not use concomitantly with other CNS stimulants. Antidiabetic drug requirements (eg, insulin) may be altered. May decrease the hypotensive effect of antihypertensives. May enhance the effects of tricyclic antidepressants. Urinary alkalinizing agents increase blood levels and decrease excretion of amphetamines. Urinary acidifying agents decrease blood levels and increase excretion of amphetamines.

Benzphetamine Adverse Reactions

Adverse Reactions

Palpitation, tachycardia, BP elevation, overstimulation, restlessness, dizziness, insomnia, tremor, sweating, headache, dry mouth, unpleasant taste, nausea, diarrhea, other GI disturbances, urticaria and other allergic reactions involving the skin, changes in libido, withdrawal effects (following prolonged high dosage administration).

Benzphetamine Clinical Trials

Clinical Trials

Adult obese patients instructed in dietary management and treated with anorectic drugs lose more weight on average than those receiving placebo and diet, as determined in relatively short-term clinical trials.

The magnitude of increased weight loss of drug-treated patients over placebo patients is only a fraction of a pound a week. The rate of weight loss is greatest in the first weeks of therapy for both drug and placebo patients and tends to decrease in succeeding weeks.

The total impact of drug-induced weight loss over that of diet alone must be considered clinically limited.

Benzphetamine Note


Formerly known under the brand name Didrex.

Benzphetamine Patient Counseling

Patient Counseling

Patients should be cautioned about concomitant use of alcohol or other CNS-active drugs and benzphetamine.

Patients should be advised to observe caution when driving or engaging in any potentially hazardous activity.