(benz FET a meen)
- Benzphetamine HCl
- Benzphetamine Hydrochloride
Excipient information presented when available (limited, particularly for generics); consult specific product labeling. [DSC] = Discontinued product
Tablet, Oral, as hydrochloride:
Didrex: 50 mg [DSC] [scored; contains fd&c yellow #6 (sunset yellow)]
Regimex: 25 mg
Generic: 25 mg, 50 mg
Brand Names: U.S.
- Didrex [DSC]
- Central Nervous System Stimulant
Benzphetamine is a sympathomimetic amine with pharmacologic properties similar to the amphetamines. The mechanism of action in reducing appetite appears to be secondary to CNS effects, including stimulation of the hypothalamus to release norepinephrine.
Use: Labeled Indications
Short-term (few weeks) adjunct to caloric restriction in exogenous obesity
Pharmacotherapy for weight loss is recommended only for obese patients with a body mass index ≥30 kg/m2, or ≥27 kg/m2 in the presence of other risk factors such as hypertension, diabetes, and/or dyslipidemia or a high waist circumference; therapy should be used in conjunction with a comprehensive weight management program.
Hypersensitivity or idiosyncrasy to benzphetamine or other sympathomimetic amines; advanced arteriosclerosis, symptomatic cardiovascular disease, moderate-to-severe hypertension; hyperthyroidism; glaucoma; agitated states, history of drug abuse; during or within 14 days following MAO inhibitor therapy, concurrent use with other CNS stimulants; women who are or may become pregnant
Obesity (short-term adjunct): Oral: Dose should be individualized based on patient response: Initial: 25-50 mg once daily; titrate to 25-50 mg 1-3 times/day; maximum dose: 50 mg 3 times/day
Refer to adult dosing.
Obesity (short-term adjunct): Children ≥12 years: Refer to adult dosing.
Dosing: Renal Impairment
No dosage adjustment provided in manufacturer’s labeling.
Dosing: Hepatic Impairment
No dosage adjustment provided in manufacturer’s labeling.
Administer without regard to meals. For patients taking a single daily dose, administer midmorning or midafternoon based on patient’s eating habits.
Most effective when combined with a low calorie diet and behavior modification counseling. May be taken without regard to meals.
Store at room temperature of 20°C to 25°C (68°F to 77°F).
Acebrophylline: May enhance the stimulatory effect of CNS Stimulants. Avoid combination
Alkalinizing Agents: May decrease the excretion of Amphetamines. Consider therapy modification
Ammonium Chloride: May decrease the serum concentration of Amphetamines. This effect is likely due to an enhanced excretion of amphetamines in the urine. Monitor therapy
Analgesics (Opioid): Amphetamines may enhance the analgesic effect of Analgesics (Opioid). Monitor therapy
Antacids: May decrease the excretion of Amphetamines. Monitor therapy
Antihistamines: Amphetamines may diminish the sedative effect of Antihistamines. Monitor therapy
Antihypertensive Agents: Amphetamines may diminish the antihypertensive effect of Antihypertensive Agents. Monitor therapy
Antipsychotic Agents: May diminish the stimulatory effect of Amphetamines. Monitor therapy
Ascorbic Acid: May decrease the serum concentration of Amphetamines. Monitor therapy
AtoMOXetine: May enhance the hypertensive effect of Sympathomimetics. AtoMOXetine may enhance the tachycardic effect of Sympathomimetics. Monitor therapy
Bosentan: May decrease the serum concentration of CYP3A4 Substrates. Monitor therapy
Cannabinoid-Containing Products: May enhance the tachycardic effect of Sympathomimetics. Exceptions: Cannabidiol. Monitor therapy
Carbonic Anhydrase Inhibitors: May decrease the excretion of Amphetamines. Exceptions: Brinzolamide; Dorzolamide. Monitor therapy
CYP3A4 Inducers (Moderate): May decrease the serum concentration of CYP3A4 Substrates. Monitor therapy
CYP3A4 Inducers (Strong): May increase the metabolism of CYP3A4 Substrates. Management: Consider an alternative for one of the interacting drugs. Some combinations may be specifically contraindicated. Consult appropriate manufacturer labeling. Consider therapy modification
Dabrafenib: May decrease the serum concentration of CYP3A4 Substrates. Management: Seek alternatives to the CYP3A4 substrate when possible. If concomitant therapy cannot be avoided, monitor clinical effects of the substrate closely (particularly therapeutic effects). Consider therapy modification
Deferasirox: May decrease the serum concentration of CYP3A4 Substrates. Monitor therapy
Doxofylline: Sympathomimetics may enhance the adverse/toxic effect of Doxofylline. Monitor therapy
Enzalutamide: May decrease the serum concentration of CYP3A4 Substrates. Management: Concurrent use of enzalutamide with CYP3A4 substrates that have a narrow therapeutic index should be avoided. Use of enzalutamide and any other CYP3A4 substrate should be performed with caution and close monitoring. Consider therapy modification
Ethosuximide: Amphetamines may diminish the therapeutic effect of Ethosuximide. Amphetamines may decrease the serum concentration of Ethosuximide. Monitor therapy
Gastrointestinal Acidifying Agents: May decrease the serum concentration of Amphetamines. Monitor therapy
Iobenguane I 123: Sympathomimetics may diminish the therapeutic effect of Iobenguane I 123. Avoid combination
Ioflupane I 123: Amphetamines may diminish the diagnostic effect of Ioflupane I 123. Monitor therapy
Linezolid: May enhance the hypertensive effect of Sympathomimetics. Management: Reduce initial doses of sympathomimetic agents, and closely monitor for enhanced pressor response, in patients receiving linezolid. Specific dose adjustment recommendations are not presently available. Consider therapy modification
Lithium: May diminish the stimulatory effect of Amphetamines. Monitor therapy
MAO Inhibitors: May enhance the hypertensive effect of Amphetamines. While linezolid and tedizolid may interact via this mechanism, management recommendations differ from other monoamine oxidase inhibitors. Refer to monographs specific to those agents for details. Exceptions: Linezolid; Tedizolid. Avoid combination
Methenamine: May decrease the serum concentration of Amphetamines. This effect is likely due to an enhanced excretion of amphetamines in the urine. Monitor therapy
Mitotane: May decrease the serum concentration of CYP3A4 Substrates. Management: Doses of CYP3A4 substrates may need to be adjusted substantially when used in patients being treated with mitotane. Consider therapy modification
Multivitamins/Fluoride (with ADE): May decrease the serum concentration of Amphetamines. More specifically, the ascorbic acid (vitamin C) in many multivitamins may decrease amphetamine concentrations. Monitor therapy
Multivitamins/Minerals (with ADEK, Folate, Iron): May decrease the serum concentration of Amphetamines. Monitor therapy
Multivitamins/Minerals (with AE, No Iron): May decrease the serum concentration of Amphetamines. Specifically, vitamin C may impair absorption of amphetamines. Monitor therapy
Siltuximab: May decrease the serum concentration of CYP3A4 Substrates. Monitor therapy
St John's Wort: May decrease the serum concentration of CYP3A4 Substrates. Management: Consider an alternative for one of the interacting drugs. Some combinations may be specifically contraindicated. Consult appropriate manufacturer labeling. Consider therapy modification
Sympathomimetics: May enhance the adverse/toxic effect of other Sympathomimetics. Monitor therapy
Tedizolid: May enhance the hypertensive effect of Sympathomimetics. Tedizolid may enhance the tachycardic effect of Sympathomimetics. Monitor therapy
Tocilizumab: May decrease the serum concentration of CYP3A4 Substrates. Monitor therapy
Tricyclic Antidepressants: May enhance the stimulatory effect of Amphetamines. Tricyclic Antidepressants may also potentiate the cardiovascular effects of Amphetamines. Monitor therapy
Urinary Acidifying Agents: May decrease the serum concentration of Amphetamines. Monitor therapy
Frequency not defined.
Cardiovascular: Cardiomyopathy (with chronic amphetamine use), hypertension, ischemic heart disease (with chronic amphetamine use), palpitations, tachycardia
Central nervous system: Depression (with withdrawal), dizziness, headache, insomnia, overstimulation, psychosis (rare), restlessness
Dermatologic: Dermatological reaction, diaphoresis, urticaria
Endocrine & metabolic: Change in libido
Gastrointestinal: Diarrhea, dysgeusia, nausea, xerostomia
Neuromuscular & skeletal: Tremor
Concerns related to adverse effects:
• CNS effects: Amphetamines may impair the ability to engage in potentially hazardous activities (eg, driving or operating machinery).
• Primary pulmonary hypertension (PPH): A rare, frequently fatal disease of the lungs, PPH has been found to occur with increased frequency in patients receiving some anorexigens. Risk increases with therapy >3 months and repeated therapy. Patients experiencing onset/aggravation of exertional dyspnea or unexplained angina, edema (lower extremity), or syncope, should discontinue therapy immediately and be evaluated for presence of pulmonary hypertension.
• Valvular heart disease: The use of some anorexigens has been associated with the development of valvular heart disease. Risk is increased with long duration of therapy, exceeding recommended dosing, and combination use with other anorexigens. Avoid stimulants in patients with known serious structural cardiac abnormalities, cardiomyopathy, serious heart rhythm abnormalities, or other serious cardiac problems that could increase the risk of sudden death that these conditions alone carry.
• Diabetes: Use with caution in patients with diabetes mellitus; antidiabetic agent requirements may be altered with anorexigens and concomitant dietary restrictions.
• Hypertension: Use with caution in patients with hypertension and other cardiovascular conditions that might be exacerbated by increases in blood pressure or heart rate.
• Seizure disorders: Use with caution in patients with a history of seizure disorders.
• Tourette's syndrome: Use with caution in patients with Tourette's syndrome; stimulants may unmask tics.
Concurrent drug therapy issues:
• Anorexigens: Do not use in combination with other weight loss medications, including prescribed, over-the-counter or herbal products. Not recommended for use in patients who have used other anorectic agents within the past year.
• Elderly: Use caution due to risk of causing dependence, hypertension, angina, and myocardial infarction.
• Abuse potential: Benzphetamine is pharmacologically related to the amphetamines, which have a high abuse potential; prolonged use may lead to dependency. Prescriptions should be written for the smallest quantity consistent with good patient care to minimize possibility of overdose.
• Discontinuation of therapy: Discontinue if satisfactory weight loss (≥4 pounds) has not occurred within the first 4 weeks of treatment, or if tolerance develops.
Cardiac evaluation (baseline), echocardiogram (during and after treatment), blood pressure; weight, waist circumference
Pregnancy Risk Factor
Use is contraindicated in women who are or may become pregnant. Adverse events were observed in animal reproduction studies.
• Discuss specific use of drug and side effects with patient as it relates to treatment. (HCAHPS: During this hospital stay, were you given any medicine that you had not taken before? Before giving you any new medicine, how often did hospital staff tell you what the medicine was for? How often did hospital staff describe possible side effects in a way you could understand?)
• Patient may experience dry mouth, insomnia, diarrhea, nausea, agitation, tremors, sweating a lot, or bad taste. Have patient report immediately to prescriber angina, tachycardia, abnormal heartbeat, severe dizziness, passing out, mood changes, behavioral changes, severe anxiety, severe headache, decreased libido, shortness of breath, or swelling of arms or legs (HCAHPS).
• Educate patient about signs of a significant reaction (eg, wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat). Note: This is not a comprehensive list of all side effects. Patient should consult prescriber for additional questions.
Intended Use and Disclaimer: Should not be printed and given to patients. This information is intended to serve as a concise initial reference for health care professionals to use when discussing medications with a patient. You must ultimately rely on your own discretion, experience, and judgment in diagnosing, treating, and advising patients.