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Active ingredient: Methylphenidate - Brands, Medical Use, Clinical Data

Brands, Medical Use, Clinical Data

Drug Category

  • Adrenergic Agents
  • Adrenergic Uptake Inhibitors
  • Central Nervous System Stimulants
  • Dopamine Uptake Inhibitors
  • Sympathomimetics

Dosage Forms

  • Tablets
  • Tablets (sustained release)

Brands / Synonyms

4311/B Ciba; Calocain; Centedein; Centedrin; Centedrine; Centredin; Concerta; Focalin; Focalin XR; Meridil; Metadate; Metadate CD; Metadate ER; Methyl phenidyl acetate; Methylin; Methylin ER; Methylofenidan; Methylphen; Methylphenidan; Methylphenidate; Methylphenidate HCl; Methylphenidate hydrochloride; Methylphenidatum [Inn-Latin]; Methylphenidylacetate hydrochloride; Methypatch; Metilfenidat hydrochloride; Metilfenidato [Inn-Spanish]; Metilfenidato [Italian]; Phenidylate; Plimasine; PMS-Methylphenidate; Riphenidate; Ritalin; Ritalin hydrochloride; Ritalin LA; Ritalin SR; Ritalin-SR; Ritaline; Ritcher Works

Indications

For use as an integral part of a total treatment program which typically includes other remedial measures (psychological, educational, social) for a stabilizing effect in children with a behavioral syndrome characterized by the following group of developmentally inappropriate symptoms: moderate-to-severe distractibility, short attention span, hyperactivity, emotional lability, and impulsivity.

Pharmacology

Methylphenidate is a central nervous system stimulant used most commonly in the treatment of attention-deficit disorders in children and for narcolepsy. Its mechanisms appear to be similar to those of dextroamphetamine.

Mechanism of Action

Methylphenidate blocks dopamine uptake in central adrenergic neurons by blocking dopamine transport or carrier proteins. Methylphenidate acts at the brain stem arousal system and the cerebral cortex and causes increased sympathomimetic activity in the central nervous system. Alteration of serotonergic pathways via changes in dopamine transport may result.

Absorption

Readily absorbed in a biphasic manner. It reaches peak absorption at approximately two hours for the first phase and five hours for the second phase. Bioavailability is low (approximately 30%)

Toxicity

Symptoms of overdose include vomiting, agitation, tremors, hyperreflexia, muscle twitching, convulsions (may be followed by coma), euphoria, confusion, hallucinations, delirium, sweating, flushing, headache, hyperpyrexia, tachycardia, palpitations, cardiac arrhythmias, hypertension, mydriasis, and dryness of mucous membranes. LD50=190mg/kg (orally in mice)

Biotrnasformation / Drug Metabolism

Hepatic, methylphenidate is metabolized primarily by de-esterification to ritalinic acid (α-phenyl-2-piperidine acetic acid, PPAA), which has little to no pharmacologic activity.

Contraindications

Marked anxiety, tension, and agitation are contraindications to Ritalin, since the drug may aggravate these symptoms. Ritalin is 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 Touretteís syndrome.

Ritalin is contraindicated during treatment with monoamine oxidase inhibitors, and also within a minimum of 14 days following discontinuation of a monoamine oxidase inhibitor (hypertensive crises may result).

Drug Interactions

Ritalin may decrease the hypotensive effect of guanethidine. Use cautiously with pressor agents.

Human pharmacologic studies have shown that Ritalin may inhibit the metabolism of coumarin anticoagulants, anticonvulsants (phenobarbital, diphenylhydantoin, primidone), phenylbutazone, and tricyclic drugs (imipramine, clomipramine, desipramine). Downward dosage adjustments of these drugs may be required when given concomitantly with Ritalin.

Serious adverse events have been reported in concomitant use with clonidine, although no causality for the combination has been established. The safety of using methylphenidate in combination with clonidine or other centrally acting alpha-2 agonists has not been systemically evaluated.

 

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