Dexmethylphenidate

Pronunciation

(dex meth il FEN i date)

U.S. Brand Names

Focalin™

Synonyms

Dexmethylphenidate Hydrochloride

Generic Available

No

Use

Treatment of attention-deficit/hyperactivity disorder (ADHD)

Restrictions

C-II

Pregnancy Risk Factor

C

Pregnancy Implications

Safety and efficacy have not been established in pregnant women; use only if the potential benefit to the mother outweighs the possible risks to the fetus.

Lactation

Excretion in breast milk unknown/use caution

Contraindications

Hypersensitivity to dexmethylphenidate, methylphenidate, or any component of the formulation; marked anxiety, tension, and agitation; glaucoma, motor tics, family history or diagnosis of Tourette's syndrome; use during or within 14 days following MAO inhibitor therapy

Warnings/Precautions

Recommended to be used as part of a comprehensive treatment program for ADHD. Use with caution in patients with bipolar disorder, diabetes mellitus, cardiovascular disease, hyperthyroidism, seizure disorders, insomnia, porphyria, or hypertension. Use caution in patients with history of ethanol or drug abuse. May exacerbate symptoms of behavior and thought disorder in psychotic patients. Do not use to treat severe depression or fatigue states. Potential for drug dependency exists - avoid abrupt discontinuation in patients who have received for prolonged periods. Visual disturbances have been reported with methylphenidate (rare). Stimulant use has been associated with growth suppression. Stimulants may unmask tics in individuals with coexisting Tourette's syndrome. Safety and efficacy in children <6 years of age not established.

Adverse Reactions

>10%: Gastrointestinal: Abdominal pain (15%)

1% to 10%:

Central nervous system: Fever (5%)

Gastrointestinal: Nausea (9%), anorexia (6%)

Adverse effects seen with methylphenidate (frequency not defined):

Cardiovascular: Angina, cardiac arrhythmia, cerebral arteritis, cerebral occlusion, hyper-/hypotension, palpitation, pulse increase/decrease, tachycardia

Central nervous system: Depression, dizziness, drowsiness, fever, headache, insomnia, nervousness, neuroleptic malignant syndrome (NMS), Tourette's syndrome, toxic psychosis

Dermatologic: Erythema multiforme, exfoliative dermatitis, hair loss, rash, urticaria

Endocrine & metabolic: Growth retardation

Gastrointestinal: Abdominal pain, anorexia, nausea, vomiting, weight loss

Hematologic: Anemia, leukopenia, thrombocytopenic purpura

Hepatic: Abnormal liver function tests, hepatic coma, transaminases increased

Neuromuscular & skeletal: Arthralgia, dyskinesia

Ocular: Blurred vision

Renal: Necrotizing vasculitis

Respiratory: Cough increased, pharyngitis, sinusitis, upper respiratory tract infection

Miscellaneous: Hypersensitivity reactions

Overdosage/Toxicology

Signs and symptoms of overdose may include agitation, cardiac arrhythmias, coma, confusion, convulsions, delirium, dry mucous membranes, euphoria, flushing, hallucinations, headache, hyper-reflexia, hyperpyrexia, hypertension, muscle twitching, mydriasis, palpitations, sweating, tachycardia, tremors and vomiting. Treatment is symptom-directed and supportive.

Drug Interactions

Antihypertensive agents: Effectiveness of antihypertensive agent may be decreased; use with caution

Carbamazepine: Carbamazepine may decrease the serum concentration of methylphenidate.

Clonidine: Severe toxic reactions have been reported in combined use with methylphenidate.

Linezolid: Due to MAO inhibition (see note on MAO inhibitors), concurrent use with methylphenidate should generally be avoided

MAO inhibitors: Severe hypertensive episodes have occurred with amphetamine when used in patients receiving nonselective MAO inhibitors; methylphenidate may be less likely to interact, or reactions may be less severe; use with caution only when warranted; wait 14 days following discontinuation of MAO inhibitor

Phenobarbital: Serum levels may be increased by methylphenidate (in some patients); monitor

Phenytoin: Serum levels may be increased by methylphenidate (in some patients); monitor

Selegiline: When selegiline is used at low dosages (<10 mg/day), an interaction with methylphenidate is less likely than with nonselective MAO inhibitors (see MAO inhibitor information), but theoretically possible; monitor

Sibutramine: Potential for reactions noted with amphetamines (severe hypertension and tachycardia) appears to be low; use with caution

Tricyclic antidepressants: Methylphenidate may increase serum concentrations of some tricyclic agents; clinical reports of toxicity are limited; dosage reduction of tricyclic antidepressants may be required; monitor

Venlafaxine: NMS has been reported in a patient receiving methylphenidate and venlafaxine

Warfarin: Methylphenidate may decrease metabolism of coumarin anticoagulants; effect has not been confirmed in all studies; monitor INR

Ethanol/Nutrition/Herb Interactions

Ethanol: Avoid ethanol (may cause CNS depression).

Food: High-fat meal may increase time to peak concentration.

Herb/Nutraceutical: Avoid ephedra (may cause hypertension or arrhythmias) and yohimbe (also has CNS stimulatory activity).

Stability

Store at 25°C (77°F); protect from light and moisture

Mechanism of Action

Dexmethylphenidate is the more active, d-threo-enantiomer, of racemic methylphenidate. It is a CNS stimulant; blocks the reuptake of norepinephrine and dopamine, and increases their release into the extraneuronal space.

Pharmacodynamics/Kinetics

Absorption: Rapid

Metabolism: Via de-esterification to inactive metabolite, d--phenyl-piperidine acetate (d-ritalinic acid)

Half-life elimination: 2.2 hours

Time to peak: Fasting: 1-1.5 hours

Excretion: Urine (90%)

Dosage

Oral: Children 6 years and Adults: Treatment of ADHD: Initial: 2.5 mg twice daily in patients not currently taking methylphenidate; dosage may be adjusted in 2.5-5 mg increments at weekly intervals (maximum dose: 20 mg/day); doses should be taken at least 4 hours apart

When switching from methylphenidate to dexmethylphenidate, the starting dose of dexmethylphenidate should be half that of methylphenidate (maximum dose: 20 mg/day)

Safety and efficacy for long-term use of dexmethylphenidate have not yet been established. Patients should be re-evaluated at appropriate intervals to assess continued need of the medication.

Dose reductions and discontinuation: Reduce dose or discontinue in patients with paradoxical aggravation. Discontinue if no improvement is seen after one month of treatment.

Administration

Doses should be taken at least 4 hours apart; may be taken with or without food

Monitoring Parameters

Blood pressure, heart rate, CBC with differential, platelet count; growth in children

Dietary Considerations

May be taken with or without food.

Patient Education

Take exactly as directed; do not change dosage or discontinue without consulting prescriber. Response may take some time. Avoid alcohol, caffeine, or other stimulants. Maintain adequate hydration (2-3 L/day of fluids) unless instructed to restrict fluid intake. You may experience decreased appetite or weight loss (small, frequent meals may help maintain adequate nutrition); or restlessness, impaired judgment, or dizziness (use caution when driving or engaging in tasks requiring alertness until response to drug is known). Report unresolved rapid heartbeat; excessive agitation, nervousness, insomnia, tremors, or dizziness; blackened stool; skin rash or irritation; or altered gait or movement. Pregnancy/breast-feeding precautions: Inform prescriber if you are or intend to become pregnant. Consult prescriber if breast-feeding.

Dental Health: Effects on Dental Treatment

No significant effects or complications reported

Dental Health: Vasoconstrictor/Local Anesthetic Precautions

No information available to require special precautions

Dosage Forms

Tablet, as hydrochloride: 2.5 mg, 5 mg, 10 mg