Methyl Phenidate

Methylphenidate

Mechanism :

Methylphenidate activates the brain stem arousal system and cortex to produce its stimulant effect. Methylphenidate is thought to block the reuptake of norepinephrine and dopamine into the presynaptic neuron and increase the release of these monoamines into the extraneuronal space.

Indication :

• Attention deficit hyperactivity syndrome
• Narcolepsy

Contraindications :

Marked anxiety, tension, and agitation are contraindications since the drug may aggravate these symptoms. Contraindicated also in patients known to be hypersensitive to the drug, in patients with glaucoma, and in patients with motor tics or with a family history or diagnosis of Tourette’s syndrome, during treatment with monoamine oxidase inhibitors, and also within a minimum of 14 days following discontinuation of a monoamine oxidase inhibitor.

Dosing :

Attention deficit hyperactivity disorder:

Initial: 0.3 mg/kg/dose orally before breakfast and lunch. May increase by 0.1 mg/kg/dose per week. Max dose: 60 mg/day.

Maintenance: 0.3-1 mg/kg orally before breakfast and lunch. Max dose: 2 mg/kg/day in 2 divided doses.

Narcolepsy:

>6 years: 5 mg orally, every 12 hours, may increase 5-10 mg/day every week. Max dose: 60 mg/day.

Adverse Effect :

Insomnia, decreased appetite, anxiety, dysphoria, growth retardation, abdominal pain, tics, tachycardia with palpitations, rapid increase in blood pressure, auditory hallucinations, paranoid psychosis.

Interaction :

Guanethidine: May decrease the hypotensive effect of guanethidine.
Coumarin Anticoagulants, Anticonvulsants (Phenobarbital, Diphenylhydantoin, Primidone), Phenylbutazone, and Tricyclic Drugs (Imipramine, Clomipramine, Desipramine): May inhibit the metabolism.
Clonidine: Serious adverse events have been reported in concomitant use with clonidine.

Hepatic Dose :