Dexmethylphenidate
Mechanism :
Dexmethylphenidate hydrochloride is a central nervous system stimulant. It is thought to block the reuptake of norepinephrine and dopamine into the presynaptic neuron and increase the release of these monoamines into the extra neuronal space.
Indication :
- Attention deficit hyperactivity syndrome
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 :
Oral
Immediate release tablet:
Initial: 2.5 mg twice a day, with an interval of at least 4 hours between doses.
Maintenance: Dosage may be adjusted in 2.5 to 5 mg increments at approximately weekly intervals. Maximum dose: 10 mg twice a day.
Extended-release:
6 to 18 years:
Initial: 5 mg once a day (in the morning).
Maintenance: Dosage may be adjusted in 5 mg increments at approximately weekly intervals. Maximum dose: 30 mg per day.
Adverse Effect :
Insomnia, anxiety, dysphoria, decreased appetite, growth retardation, headache, abdominal pain (usually transitory), thrombocytopenia tics and precipitation of Tourette’s syndrome. Increased blood pressure, tachycardia, palpitations, auditory hallucinations, paranoid psychosis and occasional rebound hyperactivity after each dose.
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 :
Use with caution as dexmethylphenidate is metabolized by the liver.