Pharmacodynamics

Ritalin (methylphenidate hcl) is a mild central nervous system stimulant.

The mode of action in man is not completely understood, but Ritalin (methylphenidate hcl) presumably activates the brain stem arousal system and cortex to produce its stimulant effect.

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

Effects on QT Interval

The effect of Focalin® XR (dexmethylphenidate, the pharmacologically active < tf-enantiomer of Ritalin (methylphenidate hcl) ) on the QT interval was evaluated in a double-blind, placebo- and open label active (moxifloxacin)-controlled study following single doses of Focalin® XR 40mg in 75 healthy volunteers. ECGs were collected up to 12 h post-dose. Frederica's method for heart rate correction was employed to derive the corrected QT interval (QTcF). The maximum mean prolongation of QTcF intervals was < 5 ms, and the upper limit of the 90% confidence interval was below 10 ms for all time matched comparisons versus placebo. This was below the threshold of clinical concern and there was no evident-exposure response relationship.

Pharmacokinetics

Ritalin (methylphenidate hcl) in the SR tablets is more slowly but as extensively absorbed as in the regular tablets. Relative bioavailability of the SR tablet compared to the Ritalin (methylphenidate hcl) tablet, measured by the urinary excretion of Ritalin (methylphenidate hcl) major metabolite (α-phenyl-2-piperidine acetic acid) was 105% (49%-168%) in children and 101% (85%-152%) in adults. The time to peak rate in children was 4.7 hours (1.3-8.2 hours) for the SR tablets and 1.9 hours (0.3-4.4 hours) for the tablets. An average of 67% of SR tablet dose was excreted in children as compared to 86% in adults.

In a clinical study involving adult subjects who received SR tablets, plasma concentrations of Ritalin (methylphenidate hcl) 's major metabolite appeared to be greater in females than in males. No gender differences were observed for Ritalin (methylphenidate hcl) plasma concentration in the same subjects.

Last reviewed on RxList: 1/31/2011
This monograph has been modified to include the generic and brand name in many instances.