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BENZPHETAMINE HYDROCHLORIDE

Medical Diagnosis and Drugs, Medications
BENZPHETAMINE HYDROCHLORIDE
(benz-fet'a-meen)
Didrex
Classifications: cerebral stimulant; anorexiant;
Therapeutic: anorexiant
Prototype: Amphetamine
Pregnancy Category: X
Controlled Substance: Schedule III

Availability

50 mg tablets

Action

Indirect acting sympathomimetic amine with amphetamine-like actions but with fewer side effects than amphetamine. Anorexiant effect thought to be secondary to stimulation of hypothalamus to release stored catecholamines in the CNS.

Therapeutic Effect

Effective as an appetite suppressant.

Uses

Short-term adjunct in management of exogenous obesity.

Contraindications

Known hypersensitivity to sympathomimetic amines; angle-closure glaucoma; advanced arteriosclerosis, angina pectoris, severe cardiovascular disease, moderate to severe hypertension; hyperthyroidism, agitated states; history of drug abuse; children <12 y; lactation; pregnancy (category X).

Cautious Use

Diabetes mellitus; older adults; psychosis.

Route & Dosage

Obesity
Adult: PO 25–50 mg 1–3 times/d

Administration

Oral
  • Give as a single daily dose, preferably midmorning or midafternoon, according to patient's eating habits.
  • Schedule daily dose no later than 6 h before patient retires to avoid insomnia.
  • Store in tight, light-resistant containers at 15°–30° C (59°–86° F) unless otherwise directed.

Adverse Effects (≥1%)

CNS: Euphoria, irritability, hyperactivity, nervousness, restlessness, insomnia, tremor, headache, light-headedness, dizziness, depression following stimulant effects. CV: Palpitation, tachycardia, elevated BP, irregular heartbeat. GI: Xerostomia, nausea, vomiting, diarrhea or constipation, abdominal cramps. Chronic Intoxication: Marked insomnia, irritability, hyperactivity, personality changes, psychosis, severe dermatoses.

Interactions

Drug: Acetazolamide, sodium bicarbonate decrease amphetamine elimination; ammonium chloride, ascorbic acid increase amphetamine elimination; barbiturates may antagonize the effects of both drugs; furazolidone may increase BP effects of amphetamines, and interaction may persist for several weeks after discontinuation of furazolidone; guanethidine antagonizes antihypertensive effects; because mao inhibitors, selegiline can cause hypertensive crisis (fatalities reported); do not administer amphetamines during or within 14 d of these drugs; phenothiazines may inhibit mood-elevating effects of amphetamines; tricyclic antidepressants enhance amphetamine effects because they increase norepinephrine release; beta agonists increase amphetamine's adverse cardiovascular effects.

Pharmacokinetics

Absorption: Readily absorbed from GI tract. Duration: 4 h. Metabolism: Via CYP3A4. Elimination: Renal elimination.

Nursing Implications

Assessment & Drug Effects

  • Assess for signs of excessive CNS stimulation: insomnia, restlessness, tremor, palpitations. These may indicate need for dosage adjustment.
  • Monitor vital signs; report elevated BP, tachycardia, and irregular heart rhythm.
  • Monitor diabetics for loss of glycemic control.

Patient & Family Education

  • Note: Anorexiant effects are temporary and tolerance may occur; long-term use is not indicated.
  • Do not drive or engage in potentially hazardous activities until response to drug is known.
  • Do not terminate high dosage therapy abruptly; GI distress, stomach cramps, trembling, unusual tiredness, weakness, and mental depression may result.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

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