Methylphenidate HCl, also known by the brand names Ritalin®, Concerta®, Daytrana® and Metadate, is most frequently prescribed for attention deficit disorder, although it is also sometimes used as an adjunct treatment for narcolepsy and depression. A mild central nervous system stimulant, methylphenidate is available in 5 mg, 10 mg, and 20 mg immediate-release doses. The drug is also available in enterically-coated, sustained and extended release tablets, reducing the re-dosing frequency required. A methylphenidate HCl patch has also been developed as a sustained release option for children that are unable to swallow capsules. Dosage considerations for medicines containing methylphenidate depend on which of these forms is used in addition to other factors such as age and need for treatment.
For children 6 years or older, chewable tablets should be used twice daily, preferably 30 minutes before meals. Initially, each dose should be between 2.5 to 5 mg, adjusted upward in 5 to 10 mg increments once weekly up to a maximum of 60 mg daily. Insomnia, one common side-effect of the medication, can be reduced by taking the last dose before 6 pm each day. Initial doses for sustained release tablets should be equivalent to the total dose of the chewable tablets used within an eight hour period, while also equivalent to the total daily methylphenidate dose. Extend and sustained release tablets lose their slow-release properties if crushed or chewed.
For children using transdermally absorbed methylphenidate patches, the starting methylphenidate dose should be 10 mg in a nine hour period, removed earlier if desired. The dose may be increased to 15 mg after the first week, 20 mg after the second week, and 30 mg after the third week until a sufficient methylphenidate dose is achieved. The patch should never be left on for more than nine hours, as psychoactive levels of the drug will remain in the bloodstream for up to two hours after the patch is removed.
The dose for the treatment of narcolepsy in adults is significantly higher than required for the treatment of attention deficit disorder. The initial dose of the chewable for narcolepsy is 10 mg two to three times daily, taken prior to meals to enhance absorption. Maintenance doses may be taken throughout the day as needed, provided that the total daily dose does not exceed 60 mg per day. Extended and sustained release tablets should equal the daily methylphenidate dose of chewable tablets required to treat narcolepsy symptoms.
While one of the more common off-label uses of methylphenidate is as complementary treatment for depression, it has not received approval by the United States Food and Drug Administration (USFDA) for this purpose. There are therefore no official guidelines for determining a sufficient dose in the treatment of depression. Since methylphenidate is a stimulant, it may interact with other stimulant antidepressants such as bupropion, requiring that the dosage be reduced.