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Monday, February 7, 2011

dextroamphetamine sulfate

Posted by Sampil 5:20 PM, under | No comments

dextroamphetamine sulfate
(dex troe am fet' a meen)
Dexedrine, Dexedrine SpansuleDextroStat

Pregnancy Category C
Controlled Substance C-II

Drug classes
Amphetamine
CNS stimulant

Therapeutic actions
Acts in the CNS to release norepinephrine from nerve terminals; in higher doses also releases dopamine; suppresses appetite; increases alertness, elevates mood; often improves physical performance, especially when fatigue and sleep-deprivation have caused impairment; efficacy in hyperkinetic syndrome, attention-deficit disorders in children appears paradoxical and is not understood.

Indications
·        Narcolepsy
·        Adjunct therapy for abnormal behavioral syndrome in children (attention-deficit disorder, hyperkinetic syndrome) that includes psychological, social, educational measures

Contraindications and cautions
·        Contraindicated with hypersensitivity to sympathomimetic amines, tartrazine (Dexedrine and DextroStat); advanced arteriosclerosis, symptomatic CV disease, moderate to severe hypertension, hyperthyroidism, glaucoma, agitated states.
·        Use cautiously with history of drug abuse; pregnancy; lactation.

Available forms
Tablets—5, 10, 15 mg; SR capsules—5, 10, 15 mg

Dosages
ADULTS
·        Narcolepsy: Start with 10 mg/day PO in divided doses; increase in increments of 10 mg/day at weekly intervals. If insomnia or anorexia occurs, reduce dose. Usual dosage is 5–60 mg/day PO in divided doses. Give first dose on awakening, additional doses (one or two) q 4–6 hr; long-acting forms can be given once a day.
PEDIATRIC PATIENTS
·        Narcolepsy:
6–12 yr:
 Condition is rare in children < 12 yr; when it does occur, initial dose is 5 mg/day PO. Increase in increments of 5 mg at weekly intervals until optimal response is obtained.
>12 yr: Use adult dosage.
·        Attention-deficit disorder:
< 3 yr: Not recommended.
3–5 yr: 2.5 mg/day PO. Increase in increments of 2.5 mg/day at weekly intervals until optimal response is obtained.
> 6 yr: 5 mg PO daily–bid. Increase in increments of 5 mg/day at weekly intervals until optimal response is obtained. Dosage will rarely exceed 40 mg/day. Give first dose on awakening, additional doses (one or two) q 4–6 hr. Long-acting forms may be used once a day.

Pharmacokinetics
Route
Onset
Peak
Duration
Oral
Rapid
1–5 hr
8–10 hr

Metabolism: Hepatic; T1/2: 10–30 hr
Distribution: Crosses placenta; enters breast milk
Excretion: Urine

Adverse effects
·        CNS: Overstimulation, restlessness, dizziness, insomnia, dyskinesia, euphoria, dysphoria, tremor, headache, psychotic episodes
·        CV: Palpitations, tachycardia, hypertension
·        Dermatologic: Urticaria
·        Endocrine: Reversible elevations in serum thyroxine with heavy use
·        GI: Dry mouth, unpleasant taste, diarrhea, constipation, anorexia and weight loss
·        GU: Impotence, changes in libido
·        Other: Tolerance, psychological dependence, social disability with abuse

Interactions
·        WARNING: Hypertensive crisis and increased CNS effects if given within 14 days of MAOIs; do not give dextroamphetamine to patients who are taking or who have recently taken MAOIs
·        Decreased duration of effects if taken with urinary alkalinizers (acetazolamide, sodium bicarbonate), furazolidone
·        Decreased effects if taken with urinary acidifiers
·        Decreased efficacy of antihypertensive drugs (guanethidine) given with amphetamines

Nursing considerations
Assessment
·        History: Hypersensitivity to sympathomimetic amines, tartrazine; advanced arteriosclerosis, symptomatic CV disease, moderate to severe hypertension, hyperthyroidism, glaucoma, agitated states, history of drug abuse; lactation, pregnancy, use of MAOI in the last 14 days
·        Physical: Weight; T; skin color, lesions; orientation, affect, ophthalmic examination (tonometry); P, BP, auscultation; R, adventitious sounds; bowel sounds, normal output; thyroid function tests, blood and urine glucose, baseline ECG

Interventions
·        Ensure proper diagnosis before administering to children for behavioral syndromes. Drug should not be used until other causes (learning disability, EEG abnormalities, neurologic deficits) are ruled out.
·        Interrupt drug dosage periodically in children being treated for behavioral disorders to determine if symptomatic response still validates drug therapy.
·        Monitor growth of children on long-term amphetamine therapy.
·        Dispense the lowest feasible dose to minimize risk of overdosage; should be in a light-resistant container.
·        Ensure that patient swallows SR tablets whole; do not cut, crush, or chew.
·        Give drug early in the day to prevent insomnia.
·        Monitor BP frequently early in therapy.

Teaching points
·        Take this drug exactly as prescribed. Do not increase the dosage without consulting your health care provider. If the drug appears ineffective, consult your health care provider.
·        Do not crush or chew sustained-release or long-acting tablets.
·        Take drug (especially sustained-release form) early in the day to avoid insomnia.
·        Avoid pregnancy while taking this drug. This drug can cause harm to the fetus.
·        You may experience these side effects: Nervousness, restlessness, dizziness, insomnia, impaired thinking (may diminish in a few days; avoid driving or engaging in activities that require alertness); headache, loss of appetite, dry mouth.
·        Report nervousness, insomnia, dizziness, palpitations, anorexia, GI disturbances.

Adverse effects in Italic are most common; those in Bold are life-threatening.

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