Didrex Information

Benzphetamine (Didrex)

(Appetite Suppressant - ORAL)

Didrex is an appetite suppressant used along with diet, exercise, and behavior therapy for the short-term management of obesity.

Similar in action to Phentermine or Bontril. It has been in use since the early sixties and as with Phentermine and Bontril no serious side effects have been noted. It is considered to be the strongest of these type of weight loss drugs. Didrex (Benzphetamine) is an FDA rated class 3 drug. The lower the number, the higher the abuse risk factor (that is why heroin is class 1, and amphetamines class 2). All the other drugs listed here (except Xenical, which has a lower risk "RX" classification), are class 4. This means it supposedly has a higher risk factor.

Each Tablet, for oral administration, contains 50 mg of benzphetamine hydrochloride.

The Tablets contain the anorectic agent benzphetamine hydrochloride. Benzphetamine hydrochloride is a white crystalline powder readily soluble in water and 95% ethanol.

The chemical name for benzphetamine hydrochloride is d - N, - Dimethyl - N - (phenylmethyl) benzeneethanamine hydrochloride and its molecular weight is 275.82.

Inactive Ingredients in Didrex: Calcium Stearate, Corn Starch, Erythrosine Sodium, FD & C Yellow No. 6, Lactose, Povidone, Sorbitol.

CLINICAL PHARMACOLOGY

Benzphetamine hydrochloride 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.

Didrex brand of benzphetamine hydrochloride tablets. The natural history of obesity is measured in years, whereas the studies cited are restricted to a few weeks duration; thus, the total impact of drug-induced weight loss over that of diet alone must be considered to be clinically limited. Pharmacokinetic data in humans are not available.

INDICATIONS AND USAGE

Indicated in the management of exogenous obesity as a short term adjunct in a regimen of weight reduction based on caloric restriction. The usefulness of agents of this class should be weighed against possible risks inherent in their use such as those described below.

CONTRAINDICATIONS

Contraindicated in patients with advanced arteriosclerosis, symptomatic cardiovascular disease, moderate to severe hypertension, hyperthyroidism, known hypersensitivity or idiosyncrasy to sympathomimetic amines, and glaucoma. Benzphetamine should not be given to patients who are in an agitated state or who have a history of drug abuse. Hypertensive crises have resulted when sympathomimetic amines have been used concomitantly or within 14 days following use of monoamine oxidase inhibitors. It should not be used concomitantly with other CNS stimulants. DIDREX may cause foetal harm if administered to a pregnant woman. Amphetamines have been shown to be teratogenic and embryotoxic in mammals at high multiples of the human dose. Contraindicated in women who are or may become pregnant.

WARNINGS When tolerance to the anorectic effect develops, the recommended dose should not be exceeded in an attempt to increase the effect; rather, the drug should be discontinued.

PRECAUTIONS General: Insulin requirements in diabetes mellitus may be altered in association with use of anorexigenic drugs and the concomitant dietary restrictions. Psychological disturbances have been reported in patients who receive an anorectic agent together with a restrictive dietary regime. Information for Patients: Amphetamines may impair the ability to engage in potentially hazardous activities such as operating machinery or driving a motor vehicle.

Drug Interactions: Hypertensive crises have resulted when sympathomimetic amines have been used concomitantly or within 14 days following use of monoamine oxidase inhibitors. Didrexshould not be used concomtantly with other CNS stimulants. Amphetamines may decrease the hypotensive effect of antihypertensives. Amphetamines 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. Carcinogenesis, Mutagenesis, Impairment of Fertility: Animal studies to evaluate the potential for carcinogenesis, mutagenesis or impairment of fertility have not been performed by Pharmacia & Upjohn Company.

ADVERSE REACTIONS

The following have been associated with the use of benzphetamine hydrochloride: Cardiovascular Palpitation, tachycardia, elevation of blood pressure. There have been isolated reports of cardiomyopathy associated with chronic amphetamine use. CNS Overstimulation, restlessness, dizziness, insomnia, tremor, sweating, headache; rarely, psychotic episodes at recommended doses; depression following withdrawal of the drug. Gastrointestinal Dryness of the mouth, unpleasant taste, nausea, diarrhea, other gastrointestinal disturbances. Allergic Urticaria and other allergic reactions involving the skin. Endocrine Changes in libido.

OVERDOSAGE

Manifestations of Overdosage: Acute overdosage with amphetamines may result in restlessness, tremor, tachypnea, confusion, assaultiveness and panic states. Fatigue and depression usually follow the central stimulation. Cardiovascular effects include arrhythmias, hypertension or hypotension, and circulatory collapse. Gastrointestinal symptoms include nausea, vomiting, diarrhea, and abdominal cramps. Hyperpyrexia and rhabdomyolysis have been reported and can lead to a number of associated complications. Fatal poisoning is usually preceded by convulsions and coma. Treatment of Overdosage: Information concerning the effects of overdosage with DidrexTablets is extremely limited. The following is based on experience with other anorexiants. Management of acute amphetamine intoxication is largely symptomatic and includes sedation with a barbiturate. If hypertension is marked, the use of a nitrite or rapidly acting alpha receptor blocking agent should be considered. Experience with hemodialysis or peritoneal dialysis is inadequate to permit recommendations in this regard. Acidification of the urine increases amphetamine excretion.

DOSAGE AND ADMINISTRATION

Dosage should be individualized according to the response of the patient. The suggested dosage ranges from 25 to 50 mg one to three times daily. Treatment should begin with 25 to 50 mg once daily with subsequent increase in individual dose or frequency according to response. A single daily dose is preferably given in mid-morning or mid-afternoon, according to the patient's eating habits. In an occasional patient it may be desirable to avoid late afternoon administration. Use of benzphetamine hydrochloride is not recommended in individuals under 12 years of age.

HOW DIDREX IS SUPPLIED

Supplied as follows: 50 mg (peach, round, imprinted with DIDREX 50, scored) Bottles of 100 NDC 0009-0024-01 Bottles of 500 NDC 0009-0024-02 Store at controlled room temperature 20° to 25°C (68° to 77°F) [see USP].