Dexedrine

Description

Dexedrine is the dextro isomer of the compound d, 1-amphetamine sulfate, a sympathomimetic amine of the amphetamine group. Chemically, dextroamphetamine is d-a-methylphenethylamine, and is present in all forms of Dexedrine as eh neurtral sulfate.

Clinical Pharmacology

Amphetamines are non-catecholamine, sympathomimetic amines with CNS stimulant activity. Peripheral actions include elevations of systolic and diastolic blood pressures and weak bronchodilator and respiratory stimulant action.

There is neither specific evidence which clearly establishes the mechanism whereby amphetamines produce mental and behavioral effects in children, nor conclusive regarding how these effects relate to the condition of the central nervous system.

Dexedrine (dextroamphetamine sulfate) Spansule capsules are formulated to release the active drug substance in vivo in a more gradual fashion than the standard formation, as demonstrated by blood levels. The formulation has not been shown superior in effectiveness over the same dosage of the standard, noncontrolled release formulations given in divided doses.

Indications

DEXEDRINE IS INDICATED:
1. In Narcolepsy
2. In Attention Deficit Disorder with Hyperactivity,as an integral part of a total treatment program which typically includes other remedial measures (psychological, educational, social) for a stabilizing effect in pediatric patients (ages 3 to 16) with a behavioral syndrome characterized by the following group of developmentally inappropriate symptoms:

moderate to severe distractiblity
short attention span
hyperactivity
emotional lability
impulsivity

The diagnosis of this syndrome should not be made with finality when these symptoms are only of comparatively recent origin. Nonlocalizing (soft) neurological signs, learning disability, and abnormal EEG may or may not be present, and a diagnosis of central nervous system dysfunction may or may not be warranted.

Dosage and Administration

Amphetamines should be administered at the lowest effective dosage and dosage should be individually adjusted. Late evening doses, particularly with the Spanule capsule form should be avoided because of the resulting insomnia.

Narcolepsy

Usual dose 5 to 60 mg per day in divided doses, depending on the individual patient response.

Narcolepsy seldom occurs in children under 12 years of age; however, when it does Dexedrine may be used. The suggested intial dose for patients aged 6 to 12 is 5 mg daily; daily dose may be raised in increments of 5 mg weekly intervals until optimal response is obtained. In patients 12 and older, start with 10 mg daily; daily dosage may be raised in increments of 10 mg at weekly intervals until optimal response is obtained. If bothersome adverse reactions appear (e.g. insomia or anorexia), dosage should be reduced. Spanule capsules may be used for once a day dosage wherever appropriate. With tablets give first dose on awakening, additional doses (1 or 2)at intervals of 4 to 6 hours.

Attention Deficit with Hyperactivity

Not recommended for pediatric patients under 3 years of age.

In pediatric patients from 3 to 5 years of age, start with 2.5 mg daily, by tablet daily dosage may be raised in increments of 2.5 mg at weekly intervals until optimal response is obtained.

In pediatric patients 6 years of age or older, start with 5 mg once or twice daily, daily dosage may be raised in increments of 5 mg at weekly intervals until optimal response is obtained. Only in rare cases will it be necessary to exceed a total of 40 mg per day.

Spansule capsules may be used for once a day dosage wherever appropriate. With tablets, give first dose on awakening and additional doses (1 or 2) at intervals of 4 to 6 hours.

Where possible drug administration should be interrupted occasionally to determine if there is a recurrence of behavioral symptoms sufficient to require continued therapy.

How Supplied

Dexedrine Spansule Capsules

5 mg capsule: imprinted 5 mg and 3512 on the brown cap and is imprinted 5 mg and SB on the clear body.
10 mg capsule: imprinted 10 mg and 3513 on the brown cap and is imprinted 10 mg and SB on the clear body.
15 mg capsule: imprinted 15 mg and 3514 on the brown cap and is imprinted 15 mg and SB on the clear body.

Dexedrine Tablets Triangular, orange, scored, debossed SKF and E19.

Adverse Reactions

Cardiovascular
Palpitations, tachycardia, elevation of blood pressure. There have been isolated reports of cardiomyopathy associated with chronic amphetamine use.
Central Nervous System
Psychotic episodes at recommended doses (rare), overstimulation, restlessness, dizziness, insomnia, euphoria, dyskinesia, dysphoria, tremor, headache, exacerbation of motor and phonic tics and Tourette's syndrome.
Gastrointestinal
Dryness of the mouth, unpleasant taste, diarrhea, constipation, other gastrointestinal distrubances. Anorexia and weight loss may occur as undesirable effects.
Allergic
Urticaria
Endocrine
Impotence, changes in libido.

Drug Interactions

Acidifying Agents: gastrointestinal acidifying agents (guanethidine, reserpine, glutamic acid HCI, ascorbic acid, fruit juices, etc.) lower absorption of amphetamines, Urinary acidifying agents (ammonium chloride, sodium acid phosphate, etc.) increase the concentration of the ionized species of the amphetamine molecule, thereby increasing urinary excretion. Both groups of agents lower blood levels and efficacy of amphetamines.
Adrenergic Blockers: adrenergic blockers are inhibited by amphetamines.
Alkalinizing Agents: gastrointestinal alkalinizing agents (sodium bicarbonate, etc.) increase absorption of amphetamines. Urinary alkalinizing agents (acetazolamide, some thiazides) increase the concentration of the non-ionized species of the amphetamine molecule, thereby decreasing urinary excretion. Both groups of agents increase blood levels and therefore potentiate the action of amphetamines.
Antidepressants tricyclic: amphetamines may enhance the activity of tricyclic or sympathometic agents; d-amphetamine with desipramine or protriptyline and possibly other tricyclics cause striking and sustained increases in the concentration of d-amphetamine in the brain; cardiovascular effects can be potentiated.
MAO Inhibitors: MAOI antidepressants, as well as a metabolite of furazolidone, slow amphetamine metabolism. This slowing potentiates amphetamines, increasing their effect on the release of norepinephrine and other monoamines from adrenergic nerve endings; this can cause headaches and other signs of hypertensive crisis. A variety of neurological toxic effects and malignant hyperpyrexia can occur, sometimes with fatal results.
Antihistamines: amphetamines may counteract the sedative effect of antihistamines.
Antihypertensives: amphetamines may antagonize the hypotensive effects of antihypertensives.
Chlorpromazine: chlorpromazine blocks dopamine and norepinephrine reuptake, thus inhibiting the central stimulant effects of amphetamines, and can be used to treat amphetamine poisoning.
Ethosuximide: amphetamines may delay intestinal absorption of ethosuximide.

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