RITALIN LA CAPSULE 20mg

Methylphenidate

Source of information: Drugbank (External Link). Last updated on: 3rd July 18
*Trade Name used in the content below may not be the same as the HSA-registered product.

Active Ingredient / Synonyms

Methyl phenidylacetate | methyl phenyl(piperidin-2-yl)acetate | methyl α-phenyl-α-(2-piperidyl)acetate | methyl α-phenyl-α-2-piperidinylacetate | Methylphenidan | Methylphenidatum | Metilfenidato | MPH | α-phenyl-2-piperidineacetic acid methyl ester | Methylphenidate |

Description

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.

Indication

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.

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.

Pharmacodynamics

Methylphenidate is a central nervous system stimulant used most commonly in the treatment of attention-deficit disorders in children and for narcolepsy. Methylphenidate also blocks the reuptake of norepinephrine and dopamine. Its mechanisms appear to be similar to those of dextroamphetamine. Furthermore, it is a racemic mixture comprised of the d- and l-threo enantiomers. The d-threo enantiomer is more pharmacologically active than the l-threo enantiomer.

Pharmacokinetics

Absorption:

Readily absorbed in a biphasic manner when orally administered (tablets) to children diagnosed with ADHD and to healthy adults. In children and adults males, after administration of a single oral dose of Ritalin LA and Ritalin given in two doses 4 hours apart, peak plasma concentration is reached approximately 2 hours for the first phase and 5-6 hours for the second phase. The absolute oral bioavailability of methylphenidate in children was 22±8% for d-methylphenidate and 5±3% for l-methylphenidate. These low values suggest that methylphenidate is highly metabolized presystemically.

Distribution:

d-methylphenidate = 2.65 L/kg; l-methylphenidate = 1.80 L/kg;

Metabolism:

Methylphenidate is hepatically metabolized. More specifically, it is rapidly and extensively metabolized by carboxylesterase CES1A1. Via this enzyme, methylphenidate undergoes de-esterification to ritalinic acid (a-phenyl-2-piperidine acetic acid, PPAA), which has little to no pharmacologic activity.

Elimination:

After oral administration of an immediate release formulation of methylphenidate, 78%-97% of the dose is excreted in the urine and 1%-3% in the feces in the form of metabolites within 48-96 hours. Only small quantities (<1%) of unchanged methylphenidate appear in the urine. Most of the dose is excreted in the urine as ritalinic acid (60%-86%), the remainder being accounted for by minor metabolites.

Half-life

d-methylphenidate = 3-4 hours; l-methylphenidate = 1-3 hours; Ritalinic acid = 3-4 hours;

Clearance

Systemic clearance for Ritalin LA and Ritalin tablets is as follows: d-methylphenidate= 0.40±0.12 L/h/kg; l-methylphenidate = 0.73±0.28 L/h/kg;

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)

References

  1. Health Science Authority of Singapore - Reclassified POM
  2. Drugbank

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Approval Information

RITALIN LA CAPSULE 20mg was registered with Health Science Authority of Singapore by NOVARTIS (SINGAPORE) PTE LTD. It is marketed with the registration number of SIN12351P with effective from 2003-07-21.

This product contains 20mg of Methylphenidate in the form of CAPSULE.

The medicine was manufactured by Alkermes Gainesville LLC in UNITED STATES

It is a Presciption Only Medicine which can only be obtained from a doctor or a dentist, or from a pharmacist with a prescription from a Singapore-registered doctor or dentist.

Anatomical Therapeutic Chemical (ATC) Classification

ATC Code: N06BA04

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