DEXMETHYLPHENIDATE

DEXMETHYLPHENIDATE
(dex-meth-ill-fen'i-date)
Focalin, Focalin XR
Classifications: cerebral stimulant;
Therapeutic: cerebral stimulant
Prototype: Amphetamine
Pregnancy Category: C
Controlled Substance: Schedule II

Availability

2.5 mg, 5 mg, 10 mg tablets; 5 mg, 10 mg, 20 mg extended release capsules

Action

Thought to block the reuptake of norepinephrine and dopamine into the presynaptic neurons and, thereby, increases release of these substances into the synapse. The mode of action in controlling the symptoms of attention deficit hyperactivity disorder (ADHD) is not fully understood.

Therapeutic Effect

Is effective in controlling ADHD syndrome in conjunction with other measures (psychological, educational, and social).

Uses

Attention deficit hyperactivity disorder (ADHD).

Contraindications

Hypersensitivity to dexmethylphenidate or methylphenidate; known structural cardiac abnormalities in children or adults, cardiomyopathy, congenital heart disease; coronary heart disease; severe agitation, anxiety, or tension; psychotic symptomatology; substance abuse; glaucoma; motor tics other than Tourette's syndrome; concurrent MAOI therapy; children <6 y; seizures; pregnancy (category C), lactation.

Cautious Use

Moderate to severe hepatic insufficiency; Tourette's syndrome; depression; emotional instability; alcoholism or drug dependence; history of seizure disorders; hypertension, CHF, cardiac arrhythmias; hyperthyroidism.

Route & Dosage

Attention Deficit Hyperactivity Disorder
Adult: PO 2.5 mg b.i.d., may increase by 2.5 mg–5 mg/d at weekly intervals to max of 20 mg/d. If converting from methylphenidate, start with ? of methylphenidate dose. Extended release: 10 mg daily, may increase by 5 mg at weekly intervals to max of 20 mg/d
Child (>6 y): PO 2.5 mg b.i.d., may increase by 2.5 mg–5 mg/d at weekly intervals to max of 20 mg/d. If converting from methylphenidate, start with ? of methylphenidate dose. Extended release: 5 mg daily, may increase by 5 mg at weekly intervals to max of 20 mg/d>

Administration

Oral

Do not administer with or within 14 d following discontinuation of an MAO inhibitor.
Give sustained release capsules whole. They should not be crushed or chewed.
Give b.i.d. doses at least 4 h apart.
Store at 15°–30° C (59°–86° F).

Adverse Effects (≥1%)

Body as a Whole: Fever, allergic reactions. CNS: Dizziness, insomnia, nervousness, tics, abnormal thinking, hallucinations, emotional lability, CNS overstimulation or sympathomimetic effects [angina, anxiety, agitation, biting, blurred vision, delirium, diaphoresis, flushing or pallor, hallucinations, hyperthermia, labile blood pressure and heart rate (hypotension or hypertension), mydriasis, palpitations, paranoia, purposeless movements, psychosis, sinus tachycardia, tachypnea, or tremor]. CV: Hypertension, tachycardia. GI: Abdominal pain, decreased appetite, nausea, vomiting.

Interactions

Drug: Additive stimulant effects with other stimulants (including amphetamine, caffeine); increased vasopressor effects with dopamine, epinephrine, norepinephrine, phenylpropanolamine, pseudoephedrine; mao inhibitors may cause hypertensive crisis; antagonizes hypotensive effects of guanethidine, bretylium; may inhibit metabolism and increase serum levels of fosphenytoin, phenytoin, phenobarbital, and primidone, warfarin, tricyclic antidepressants.

Pharmacokinetics

Absorption: Well absorbed. Peak: 1–1.5 h. Metabolism: De-esterified in liver. No interaction with CYP450 system. Elimination: Primarily in urine. Half-Life: 2.2 h.

Nursing Implications

Assessment & Drug Effects

Withhold drug and notify physician if patient has a seizure. Monitor closely for loss of seizure control with a prior history of seizures.
Monitor BP in all patients receiving this drug. Monitor cardiac status and report palpitations or other signs of arrhythmias.
Monitor for potential abuse and dependence on this drug. Careful supervision is needed during drug withdrawal since severe depression may occur.
Monitor for signs of aggression or psychotic behavior in adolescents and children.
Lab tests: Periodic CBC, differential, platelet counts, and LFTs during prolonged therapy.
Concurrent drugs: Monitor patients on BP-lowering drugs for loss of BP control. Monitor plasma levels of oral anticoagulants and anticonvulsants; doses of these drugs may need to be decreased.

Patient & Family Education

Withhold drug and report immediately any of the following signs of overdose: vomiting, agitation, tremors, muscle twitching, convulsions, confusion, hallucinations, delirium, sweating, flushing, headache, or high temperature.
Note that drug is usually discontinued if improvement is not observed after appropriate dosage adjustment over 1 mo.

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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