dextroamphetamine

[dek″stro-am-fet´ah-mēn] the dextrorotatory isomer of amphetamine" >amphetamine, having a more conspicuous stimulant effect on the central nervous system than the racemic form of amphetamine; used as the sulfate salt in the treatment of narcolepsy and attention-deficit/hyperactivity disorder. Abuse of this drug may lead to dependence.

dextroamphetamine

(dex-troe-am-fet-a-meen) dextroamphetamine,

Dexedrine

(trade name)

Classification

Therapeutic: central nervous system stimulants
Pharmacologic: amphetamines
Pregnancy Category: C

Indications

Adjunct management of ADHD.Narcolepsy.Exogenous obesity.

Action

Produces CNS stimulation by releasing norepinephrine from nerve endings. Pharmacologic effects:

CNS and respiratory stimulation,

vasoconstriction,

mydriasis (pupillary dilation),

Contraction of the urinary bladder sphincter.

Therapeutic effects

Increased motor activity and mental alertness and decreased fatigue in narcoleptic patients.Increased attention span in ADHD.

Pharmacokinetics

Absorption: Well absorbed.Distribution: Widely distributed; high concentrations in brain and CSF. Crosses the placenta; enters breast milk; potentially embryotoxic.Metabolism and Excretion: Some metabolism by the liver. Urinary excretion is pH-dependent. Alkaline urine promotes reabsorption and prolongs action.Half-life: 10–12 hr (6.8 hr in children).

Time/action profile (CNS stimulation)

ROUTE	ONSET	PEAK	DURATION
PO	1–2 hr	3 hr	2–10 hr
PO-ER	unknown	unknown	up to 24 hr

Contraindications/Precautions

Contraindicated in: Obstetric / Lactation: Pregnancy or lactation;Hyperexcitable states, including hyperthyroidism;Psychotic personalities;Suicidal or homicidal tendencies;Glaucoma;Some products contain tartrazine; avoid in patients with known hypersensitivity.Use Cautiously in: Cardiovascular disease (sudden death has occurred in children with structural cardiac abnormalities or other serious heart problems);Hypertension;Diabetes mellitus;History of substance abuse;Debilitated patients;Continual use (may produce psychological dependence or physical addiction); Geriatric: Appears on Beers list. Elderly are at ↑ risk for cardiovascular side effects.

Adverse Reactions/Side Effects

Central nervous system

hyperactivity (most frequent)
insomnia (most frequent)
restlessness (most frequent)
tremor (most frequent)
behavioral disturbances
depression
dizziness
hallucinations
headache
irritability
mania
thought disorder

Cardiovascular

sudden death (life-threatening)
palpitations (most frequent)
tachycardia (most frequent)
arrhythmias
hypertension
peripheral vasculopathy

Gastrointestinal

anorexia (most frequent)
constipation
cramps
diarrhea
dry mouth
metallic taste
nausea
vomiting

Genitourinary

erectile dysfunction
↑ libido

Dermatologic

urticaria

Neurologic

paresthesia

Miscellaneous

physical dependence
psychological dependence

Interactions

Drug-Drug interaction

↑ adrenergic effects with other adrenergics.Use with MAO inhibitors can result in hypertensive crisis.Alkalinizing the urine (sodium bicarbonate, acetazolamide ) prolongs effect.Acidification of urine (ammonium chloride, large doses of ascorbic acid ) ↓ effect.Phenothiazines may ↓ effect of dextroamphetamine.May antagonize the response to antihypertensives.↑ risk of cardiovascular side effects with beta blockers or tricyclic antidepressants.St. John's wort may ↑ serious side effects, concurrent use is not recommended.Use with caffeine-containing herbs (guarana, tea, coffee) ↑ stimulant effect.St. John's wort may ↑ serious side effects, concurrent use is not recommended.

Route/Dosage

Attention-Deficit Hyperactivity DisorderOral (Adults) 5–40 mg/day in divided doses. Sustained-release capsules should not be used as initial therapy.Oral (Children ≥6 yr) 5 mg 1–2 times daily, ↑ by 5 mg daily at weekly intervals (maximum: 40 mg/day). Sustained-release capsules should not be used as initial therapy.Oral (Children 3–5 yr) 2.5 mg/day, ↑ by 2.5 mg daily at weekly intervals (maximum: 40 mg/day).NarcolepsyOral (Adults) 5–60 mg/day single dose or in divided doses. Sustained-release capsules should not be used as initial therapy.Oral (Children ≥12 yr) 10 mg/day, ↑ by 10 mg/day at weekly intervals until response is obtained or 60 mg is reached.Oral (Children 6–12 yr) 5 mg/day, ↑ by 5 mg/day at weekly intervals until response is obtained or 60 mg is reached.Exogenous obesityOral (Adults and Children >12 yr) 5–30 mg/day in divided doses of 5–10 mg given 30–60 min before meals.

Availability (generic available)

Tablets: 5 mg, 10 mg Sustained-release capsules: 5 mg, 10 mg, 15 mg

Nursing implications

Nursing assessment

Monitor BP, pulse, and respiration before administering and periodically during therapy. Obtain a history (including assessment of family history of sudden death or ventricular arrhythmia), physical exam to assess for cardiac disease, and further evaluation (ECG and echocardiogram), if indicated. If exertional chest pain, unexplained syncope, or other cardiac symptoms occur, evaluate promptly.
- Has high dependence and abuse potential. Tolerance to medication occurs rapidly; do not increase dose.
- Monitor closely for behavior change.
Geriatric: Not recommended for use in elderly secondary to risk for hypertension, angina, and MI.
ADHD: Monitor weight biweekly and inform health care professional of significant loss. Pediatric: Monitor height periodically in children; report growth inhibition.
Assess child's attention span, impulse control, and interactions with others. Therapy may be interrupted at intervals to determine whether symptoms are sufficient to continue therapy.
Narcolepsy: Observe and document frequency of narcoleptic episodes.
- May produce a false sense of euphoria and well-being. Provide frequent rest periods and observe patient for rebound depression after the effects of the medication have worn off.
Lab Test Considerations: May interfere with urinary steroid determinations.
- May cause ↑ plasma corticosteroid concentrations; greatest in evening.

Potential Nursing Diagnoses

Disturbed thought process (Side Effects)

Implementation

Therapy should utilize the lowest effective dose.
Oral: Sustained-release capsules should be swallowed whole; do not break, crush, or chew.
ADHD: Pediatric: When symptoms are controlled, dose reduction or interruption of therapy may be possible during summer months or may be given on each of the 5 school days with medication-free weekends and holidays.

Patient/Family Teaching

Instruct patient to take medication at least 6 hr before bedtime to avoid sleep disturbances. Take missed doses as soon as remembered up to 6 hr before bedtime. Do not double doses. Advise patient and parents to read the Medication Guide prior to starting therapy and with each Rx refill. Instruct patient not to alter dose without consulting health care professional. Abrupt cessation of high doses may cause extreme fatigue and mental depression.
- Inform patient that sharing this medication may be dangerous.
- Inform patients starting therapy of risk of peripheral vasculopathy. Instruct patients to notify health care professional of any new numbness; pain; skin color change from pale, to blue, to red; or coolness or sensitivity to temperature in fingers or toes, and call if unexplained wounds appear on fingers or toes. May require rheumatology consultation.
- Inform patient that the effects of drug-induced dry mouth can be minimized by rinsing frequently with water or chewing sugarless gum or candies.
- Advise patient to avoid the intake of large amounts of caffeine.
- Medication may impair judgment. Advise patients to use caution when driving or during other activities requiring alertness.
- Advise patient to notify health care professional if nervousness, restlessness, insomnia, dizziness, anorexia, or dry mouth becomes severe. Pediatric: If reduced appetite and weight loss are a problem, advise parents to provide high calorie meals when drug levels are low (at breakfast and/or bedtime).
- Advise patient and/or parents to notify health care professional of behavioral changes.
- Inform patient that periodic holiday from the drug may be ordered to assess progress and decrease dependence.
- Advise patient to notify health care professional if pregnancy is planned or suspected, or if breast feeding.
- Caution patients to inform health care professional if they have ever abused or been dependent on alcohol or drugs, or if they are now abusing or dependent on alcohol or drugs.
- Emphasize the importance of routine follow-up exams to monitor progress.
Home Care Issues: Advise parents to notify school nurse of medication regimen.

Evaluation/Desired Outcomes

Improved attention span. Therapy should be interrupted and reassessed periodically.
Decrease in narcoleptic symptoms.