Methylphenidate Hydrochloride

METHYLPHENIDATE HYDROCHLORIDE- methylphenidate hydrochloride tablet, chewable
XLCare Pharmaceuticals, Inc

DESCRIPTION

Methylphenidate HCl is a mild central nervous system (CNS) stimulant, available as 2.5 mg, 5 mg and 10 mg chewable tablets for oral administration. Methylphenidate hydrochloride is methyl α-phenyl-2-piperidineacetate hydrochloride, and its structural formula is

Structure
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Methylphenidate hydrochloride USP is a white, odorless, fine crystalline powder. Its solutions are acid to litmus. It is freely soluble in water and in methanol, soluble in alcohol, and slightly soluble in chloroform and in acetone.

Each methylphenidate hydrochloride chewable tablet, for oral administration, contains 2.5 mg, 5 mg or 10 mg of methylphenidate hydrochloride USP. In addition, methylphenidate hydrochloride chewable tablets also contain the following inactive ingredients: aspartame, lactose anhydrous, microcrystalline cellulose, guar gum, grape flavor, pregelatinized starch, and stearic acid.

CLINICAL PHARMACOLOGY

Methylphenidate 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.

Methylphenidate HCl is a central nervous system (CNS) stimulant.

The mode of therapeutic action in humans is not completely understood, but methylphenidate presumably 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.

There is neither specific evidence which clearly establishes the mechanism whereby methylphenidate hydrochloride chewable tablets produces its mental and behavioral effects in children, nor conclusive evidence regarding how these effects relate to the condition of the central nervous system.

Pharmacokinetics

Absorption

Methylphenidate hydrochloride chewable tablets are readily absorbed. Following oral administration of methylphenidate hydrochloride chewable tablets, peak plasma methylphenidate concentrations are achieved at about 1 to 2 hours. Methylphenidate hydrochloride chewable tablets have been shown to be bioequivalent to Ritalin® tablet. The mean Cmax following a 20 mg dose is approximately 10 ng/mL.

Food Effect

In a study in adult volunteers investigating the effects of a high-fat meal on the bioavailability of methylphenidate hydrochloride chewable tablets at a dose of 20 mg, the presence of food delayed the peak concentrations by approximately 1 hour (1.5 hours, fasted and 2.4 hours, fed). Overall, a high-fat meal increased the AUC of methylphenidate hydrochloride chewable tablets by about 20%, on average. Through a cross-study comparison, the magnitude of food effect is found to be comparable between the methylphenidate hydrochloride chewable tablets and Ritalin® , the immediate release tablet.

Metabolism and Excretion

In humans, methylphenidate is metabolized primarily via deesterification to alpha-phenylpiperidine acetic acid (PPA, ritalinic acid). The metabolite has little or no pharmacologic activity.

After oral dosing of radiolabeled methylphenidate in humans, about 90% of the radioactivity was recovered in urine. The main urinary metabolite was PPA, accounting for approximately 80% of the dose.

The pharmacokinetics of the methylphenidate hydrochloride chewable tablets have been studied in healthy adult volunteers. The mean terminal half-life (t½ ) of methylphenidate following administration of 20 mg methylphenidate hydrochloride chewable tablets (t½ = 3 hours) is comparable to the mean terminal t½ following administration of Ritalin® (methylphenidate hydrochloride immediate-release tablets) (t½ = 2.8 hours) in healthy adult volunteers.

Special Populations

Gender – The effect of gender on the pharmacokinetics of methylphenidate after methylphenidate hydrochloride chewable tablets administration has not been studied.

Race – The influence of race on the pharmacokinetics of methylphenidate after methylphenidate hydrochloride chewable tablets administration has not been studied.

Age – The pharmacokinetics of methylphenidate after methylphenidate hydrochloride chewable tablets administration have not been studied in pediatrics.

Renal Insufficiency

There is no experience with the use of methylphenidate hydrochloride chewable tablets in patients with renal insufficiency. After oral administration of radiolabeled methylphenidate in humans, methylphenidate was extensively metabolized and approximately 80% of the radioactivity was excreted in the urine in the form of ritalinic acid. Since renal clearance is not an important route of methylphenidate clearance, renal insufficiency is expected to have little effect on the pharmacokinetics of methylphenidate hydrochloride chewable tablets.

Hepatic Insufficiency

There is no experience with the use of methylphenidate hydrochloride chewable tablets in patients with hepatic insufficiency.

INDICATIONS AND USAGE

Attention Deficit Disorders, Narcolepsy

Attention Deficit Disorders (previously known as Minimal Brain Dysfunction in Children). Other terms being used to describe the behavioral syndrome below include: Hyperkinetic Child Syndrome, Minimal Brain Damage, Minimal Cerebral Dysfunction, Minor Cerebral Dysfunction.

Methylphenidate hydrochloride is indicated 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. The diagnosis of this syndrome should not be made with finality when these symptoms are only of comparatively recent origin. Nonlocalizing (soft) neurological signs, learning disability, and abnormal EEG may or may not be present, and a diagnosis of central nervous system dysfunction may or may not be warranted.

Special Diagnostic Considerations

Specific etiology of this syndrome is unknown, and there is no single diagnostic test. Adequate diagnosis requires the use not only of medical but of special psychological, educational, and social resources.

Characteristics commonly reported include: chronic history of short attention span, distractibility, emotional lability, impulsivity, and moderate-to-severe hyperactivity; minor neurological signs and abnormal EEG. Learning may or may not be impaired. The diagnosis must be based upon a complete history and evaluation of the child and not solely on the presence of one or more of these characteristics.

Drug treatment is not indicated for all children with this syndrome. Stimulants are not intended for use in the child who exhibits symptoms secondary to environmental factors and/or primary psychiatric disorders, including psychosis. Appropriate educational placement is essential and psychosocial intervention is generally necessary. When remedial measures alone are insufficient, the decision to prescribe stimulant medication will depend upon the physician’s assessment of the chronicity and severity of the child’s symptoms.

CONTRAINDICATIONS

Marked anxiety, tension, and agitation are contraindications to methylphenidate hydrochloride, since the drug may aggravate these symptoms. Methylphenidate hydrochloride 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 Tourette’s syndrome.

Methylphenidate hydrochloride 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).

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