Dexmethylphenidate Hydrochloride (Page 4 of 6)

8.5 Geriatric Use

Dexmethylphenidate hydrochloride tablets has not been studied in the geriatric population.

9 DRUG ABUSE AND DEPENDENCE

9.1 Controlled Substance

Dexmethylphenidate hydrochloride tablets contains dexmethylphenidate hydrochloride, a Schedule II controlled substance.

9.2 Abuse

Dexmethylphenidate hydrochloride tablets has a high potential for abuse and misuse which can lead to the development of a substance use disorder, including addiction [see Warnings and Precautions (5.1)]. Dexmethylphenidate hydrochloride tablets can be diverted for non-medical use into illicit channels or distribution.

Abuse is the intentional non-therapeutic use of a drug, even once, to achieve a desired psychological or physiological effect. Misuse is the intentional use, for therapeutic purposes, of a drug by an individual in a way other than prescribed by a health care provider or for whom it was not prescribed. Drug addiction is a cluster of behavioral, cognitive, and physiological phenomena that may include a strong desire to take the drug, difficulties in controlling drug use (e.g., continuing drug use despite harmful consequences, giving a higher priority to drug use than other activities and obligations), and possible tolerance or physical dependence.

Misuse and abuse of methylphenidate may cause increased heart rate, respiratory rate, or blood pressure; sweating; dilated pupils; hyperactivity; restlessness; insomnia; decreased appetite; loss of coordination; tremors; flushed skin; vomiting; and/or abdominal pain. Anxiety, psychosis, hostility, aggression, and suicidal or homicidal ideation have also been observed with CNS stimulants abuse and/or misuse. Misuse and abuse of CNS stimulants, including Dexmethylphenidate hydrochloride tablets, can result in overdose and death [see Overdosage (10)], and this risk is increased with higher doses or unapproved methods of administration, such as snorting or injection.

9.3 Dependence

Physical Dependence

Dexmethylphenidate hydrochloride tablets may produce physical dependence. Physical dependence is a state that develops as a result of physiological adaptation in response to repeated drug use, manifested by withdrawal signs and symptoms after abrupt discontinuation or a significant dose reduction of a drug.

Withdrawal signs and symptoms after abrupt discontinuation or dose reduction following prolonged use of CNS stimulants including Dexmethylphenidate hydrochloride tablets include dysphoric mood; depression; fatigue; vivid, unpleasant dreams; insomnia or hypersomnia; increased appetite; and psychomotor retardation or agitation.

Tolerance

Dexmethylphenidate hydrochloride tablets may produce tolerance. Tolerance is a physiological state characterized by a reduced response to a drug after repeated administration (i.e., a higher dose of a drug is required to produce the same effect that was once obtained at a lower dose).

10 OVERDOSAGE

Clinical Effects of Overdose

Overdose of CNS stimulants is characterized by the following sympathomimetic effects:

  • Cardiovascular effects including tachyarrhythmias, and hypertension or hypotension. Vasospasm, myocardial infarction, or aortic dissection may precipitate sudden cardiac death. Takotsubo cardiomyopathy may develop.
  • CNS effects including psychomotor agitation, confusion, and hallucinations. Serotonin syndrome, seizures, cerebral vascular accidents, and coma may occur.
  • Life-threatening hyperthermia (temperatures greater than 104°F) and rhabdomyolysis may develop.

OverdoseManagement

Consider the possibility of multiple drug ingestion. Because methylphenidate has a large volume of distribution and is

rapidly metabolized, dialysis is not useful. Consider contacting the Poison Help line (1-800-222-1222) or a medical toxicologist for additional overdose management recommendations.

11 DESCRIPTION

Dexmethylphenidate hydrochloride tablets contains dexmethylphenidate hydrochloride, a CNS stimulant. Dexmethylphenidate hydrochloride is the d-threo enantiomer of racemic methylphenidate hydrochloride. Dexmethylphenidate hydrochloride tablets is available as 2.5 mg, 5 mg, and 10 mg strength tablets for oral administration.

Chemically, dexmethylphenidate hydrochloride is methyl α-phenyl-2-piperidineacetate hydrochloride, (R, R’)- (+)-. Its molecular formula is C14H19NO2•HCl. Its structural formula is:

Chemical Formula
(click image for full-size original)

Note: * = asymmetric carbon centers

Dexmethylphenidate hydrochloride is a white to off-white 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. Its molecular weight is 269.77 g/mol.

Inactive ingredients: Dexmethylphenidate hydrochloride tablets also contains the following inert ingredients: lactose anhydrous, magnesium stearate, microcrystalline cellulose and pregelatinized starch. Additionally, 5 mg tablets contain D&C Yellow #10 aluminum lake; 2.5 mg tablets contains FD&C Blue #1 aluminum lake.

12 CLINICAL PHARMACOLOGY

12.1 Mechanism of Action

Dexmethylphenidate hydrochloride is a CNS stimulant. The mode of therapeutic action in ADHD is not known.

12.2 Pharmacodynamics

Pharmacodynamics

Dexmethylphenidate is the more pharmacologically active d- enantiomer of racemic methylphenidate. Methylphenidate blocks the reuptake of norepinephrine and dopamine into the presynaptic neuron and increase the release of these monoamines into the extraneuronal space.


Cardiac Electrophysiology

A formal QT study has not been conducted in patients taking dexmethylphenidate hydrochloride tablets; however, a large QT effect is not expected. At the recommended maximum total daily dosage of 40 mg, dexmethylphenidate hydrochloride extended-release capsule does not prolong the QTc interval to any clinically relevant extent.

12.3 Pharmacokinetics

Absorption

Dexmethylphenidate hydrochloride is readily absorbed following oral administration of dexmethylphenidate hydrochloride tablets. In patients with ADHD, plasma dexmethylphenidate concentrations increase rapidly, reaching a maximum in the fasted state at about 1 to 1.5 hours postdose. No differences in the pharmacokinetics of dexmethylphenidate hydrochloride tablets were noted following single and repeated twice daily dosing, thus indicating no significant drug accumulation in children with ADHD.

After single dose administration of dexmethylphenidate hydrochloride tablets to pediatric patients, dexmethylphenidate exposure (C max and AUC 0-inf ) showed dose-proportional increase in the range of 2.5 mg to 10 mg. Comparable plasma dexmethylphenidate levels were achieved following single dl-threo -methylphenidate HCl doses given as capsules in twice the total mg amount (equimolar with respect to dexmethylphenidate hydrochloride tablets).

Approximately 90% of the dose is absorbed after oral administration of radiolabeled racemic methylphenidate. However, due to first pass metabolism the mean absolute bioavailability of dexmethylphenidate when administered in various formulations was 22% to 25%.

Effect of Food

High fat breakfast did not significantly affect C max or AUC 0-inf of dexmethylphenidate when two 10 mg dexmethylphenidate hydrochloride tablets were administered, but delayed T max from 1.5 hours post dose to 2.9 hours post dose.


Distribution

The plasma protein binding of dexmethylphenidate is not known; racemic methylphenidate is bound to plasma proteins by 12% to 15%, independent of concentration. Dexmethylphenidate shows a volume of distribution of 2.65 ± 1.11 L/kg.


Elimination

Plasma dexmethylphenidate concentrations declined exponentially following oral administration of dexmethylphenidate hydrochloride tablets. Intravenous dexmethylphenidate was eliminated with a mean clearance of 0.40 ± 0.12 L/hr/kg. The mean terminal elimination half-life of dexmethylphenidate was approximately 2.2 hours.


Metabolism

In humans, dexmethylphenidate is metabolized primarily via de-esterification to d-α- phenyl-piperidine acetic acid (also known as d- ritalinic acid). This metabolite has little or no pharmacological activity. There is little or no in vivo interconversion to the l-threo- enantiomer.

Excretion

After oral dosing of radiolabeled racemic methylphenidate in humans, about 90% of the radioactivity was recovered in urine. The main urinary metabolite of racemic dl -methylphenidate was dl- ritalinic acid, accountable for approximately 80% of the dose. Urinary excretion of parent compound accounted for 0.5% of an intravenous dose.


Studies in Special Populations

Male and Female Patients

Pharmacokinetic parameters were similar for boys and girls (mean age 10 years).

In a single dose study conducted in adults, the mean dexmethylphenidate AUC 0-inf values (adjusted for body weight) following single two 10 mg doses of dexmethylphenidate hydrochloride tablets were 25% to 35% higher in adult female volunteers (n = 6) compared to male volunteers (n = 9). Both T max and t 1/2 were comparable for males and females.


Racial or Ethnic Groups

There is insufficient experience with the use of dexmethylphenidate hydrochloride tablets to detect ethnic variations in pharmacokinetics.


Pediatric Patients

The pharmacokinetics of dexmethylphenidate after dexmethylphenidate hydrochloride tablets administration have not been studied in children less than 6 years of age. When single doses of dexmethylphenidate hydrochloride tablets were given to children between the ages of 6 to 12 years and healthy adult volunteers, C max of dexmethylphenidate was similar, however, pediatric patients showed somewhat lower AUCs compared to the adults.


Patients with Renal Impairment

There is no experience with the use of dexmethylphenidate hydrochloride tablets in patients with renal impairment. Since renal clearance is not an important route of methylphenidate clearance, renal impairment is expected to have little effect on the pharmacokinetics of dexmethylphenidate hydrochloride tablets.


Patients with Hepatic Impairment
There is no experience with the use of dexmethylphenidate hydrochloride tablets in patients with hepatic impairment.

Drug Interaction Studies

Methylphenidate is not metabolized by cytochrome P450 (CYP) isoenzymes to a clinically relevant extent. Inducers or inhibitors of CYPs are not expected to have any relevant impact on methylphenidate pharmacokinetics. Conversely, the d- and l- enantiomers of methylphenidate did not relevantly inhibit CYP1A2, 2C8, 2C9, 2C19, 2D6, 2E1, or 3A. Clinically, methylphenidate coadministration did not increase plasma concentrations of the CYP2D6 substrate desipramine.

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