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Benzphetamine
DIDREX 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,-œ Dimethyl-N-(phenylmethyl)-benzeneeth-anamine hydrochloride and its molecular weight is 275.82. Each DIDREX Tablet, for oral administration, contains 50 mg of benzphetamine hydrochloride. Inactive Ingredients: Calcium Stearate, Corn Starch. Ervthrosine Sodium.
FD 8 C Yellow No.61 Lactose, Povidone, Sorbitol.
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. Drugs of this class used in obesity are commonly known as “anorectics” or “anorexigenics”. It has not been established, however, that the action of such drugs in treating obesity is primarily one of appetite suppression. Other central nervous system actions, or metabolic effects, may be involved. Adult obese subjects instructed in dietary management and treated with “anorectic” drugs, lose more weight on the average than those treated with placebo and diet, as determined in relatively short-term clinical trials. The magnitude of increased weight loss of drug-treated patients over placebo-treated patients is only a fraction of a pound a week. The rate of weight loss is the greatest in the first weeks of therapy for both drug and placebo subjects and tends to decrease in succeeding weeks. The possible origins of the increased weight loss due to the various drug effects are not established. The amount of weight loss associated with the use of an “anorectic” drug varies from trial to trial, and the increased weight loss appears to be related in proof to variables other than the drug prescribed, such as the physician-investigator, the population treated, and the diet prescribed. Studies do not permit conclusions as to the relative importance of the drug and non-drug factors on weight loss. 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.
DIDREX Tablets are 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. The limited usefulness of agents of this class (See CLINICAL PHARMACOLOGY) should be weighed against possible risks inherent in their use such as those described below.
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 recom-mended in children under 12 years of age. HOW SUPPLIED DIDREX Tablets are supplied as follows: 50 mg (peach, round, imprinted with DIDREX 50, scored)
Store at controlled room temperature 15°-30° C (59°-86° F). Caution: Federal law prohibits
dispensing without prescription.
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. DRUG ABUSE and DEPENDENCE Benzphetamine is a controlled substance under the Controlled Substance Act by the Drug Enforcement Administration and has been assigned to Schedule III. Benzphetamine hydrochloride is related chemically and pharmacologically to the amphetamines. Amphetamines and related stimulant drugs have been extensively abused, and the possibility of abuse of DIDREX Tablets 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 intoxication is psychosis, often clinically indistinguishable from schizophrenia.
Hypertensive crises have resulted when sympathomimetic amines have been used concomitanlly within14 days following use of monoamine oxidase inhibitors. DIDREX should not be used concomitantly 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.
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.
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. Caution is to be exercised in prescribing amphetamines for patients with even mild hypertension. The least amount feasible should be prescribed or dispensed at one time in order to minimize the possibility of overdosage. Information for Patients Amphetamines 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 Interactions Hypertensive crises have resulted when sympathomimetic amines have been used concomitanlly within14 days following use of monoamine oxidase inhibitors. DIDREX should not be used concomitantly 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. Carcinogenests, Mutagenesis, Impairment of Fertility Animal studies to evaluate the potential for carcinogenesis, mutagenesis or impair-ment of fertility have not been performed by The Upjohn Company. Pregnancy Pregnancy Category X. (See CONTRAINDICATIONS section). Nursing Mothers Amphetamines are excreted in human milk. Mothers taking amphetamines should be advised to refrain from nursing. Pediatric Use Use of benzphetamine hydrochloride
is not recommended in children under 12 years of age.
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