Drug information of Benzphetamine


Drug group:

A sympathomimetic agent with properties similar to dextroamphetamine. It is used in the treatment of obesity.

Mechanism of effect

Although the mechanism of action of the sympathomimetic appetite suppressants in the treatment of obesity is not fully known, these medications have pharmacological effects similar to those of amphetamines. Amphetamine and related sympathomimetic medications (such as benzphetamine) are thought to stimulate the release of norepinephrine and/or dopamine from storage sites in nerve terminals in the lateral hypothalamic feeding center, thereby producing a decrease in appetite. This release is mediated by the binding of benzphetamine to centrally located adrenergic receptors.


Benzphetamine, a phenylalkylamin, is related to amphetamine both chemically and pharmacologically. It is an anorectic agent indicated in the management of exogenous obesity as a short term adjunct (a few weeks) in a regimen of weight reduction based on caloric restriction. Benzphetamine is a sympathomimetic amine with pharmacologic activity similar to the prototype drugs of this class used in obesity, the amphetamines. Actions include central nervous system stimulation and elevation of blood pressure. Tachyphylaxis and tolerance have been demonstrated with all drugs of this class in which these phenomena have been looked for.


Metabolism: by cytochrome P450 enzymes

Excretion: 5-30% unchanged in urine, highly dependent on pH




25-50 mg PO qDay initially; may increase dose or frequency according to response up to TID



<12 years: Safety and efficacy not established

≥12 years: 25-50 mg PO qDay initially; may increase dose or frequency according to response up to TID


Discontinue when tolerance develops - DO NOT EXCEED recommended dose

Diabetics: insulin requirements may be altered

Mild hypertension

May impair ability to drive &/or operate heavy machinery

Alkaline urine will increase half-life

Points of recommendation

  • Tell all of your health care providers that you take benzphetamine. This includes your doctors, nurses, pharmacists, and dentists.
  • Avoid driving and doing other tasks or actions that call for you to be alert until you see how benzphetamine affects you.
  • If you have been taking benzphetamine for a long time or at high doses, it may not work as well and you may need higher doses to get the same effect. This is known as tolerance. Call your doctor if benzphetamine stops working well. Do not take more than ordered.
  • If you have been taking benzphetamine for many weeks, talk with your doctor before stopping. You may want to slowly stop benzphetamine.
  • People who take drugs for weight loss like benzphetamine may have a higher chance of having raised pressure in the lungs. This is rare but is often deadly. Talk with your doctor.
  • If you have high blood sugar (diabetes), you will need to watch your blood sugar closely.
  • Do not take more than what your doctor told you to take. Taking more than you are told may raise your chance of very bad side effects.
  • Follow the diet and workout plan that your doctor told you about.
  • This medicine may cause harm to the unborn baby if you take it while you are pregnant. If you are pregnant or you get pregnant while taking benzphetamine, call your doctor right away.
  • Take benzphetamine early in the day to prevent sleep problems.
  • Take with or without food.
  • Take a missed dose as soon as you think about it.
  • If it is close to the time for your next dose, skip the missed dose and go back to your normal time.
  • Do not take 2 doses at the same time or extra doses.

Ask a Pharmacist

User's questions
    No comments yet.