Ritalin is the common brand name for methylphenidate. It is related to the central nervous system (CNS) which is a stimulant of the piperidine and phenethylamine classes. Methylphenidate was approved for medical use in the United States in 1955. In 2013, approximately 2.4 billion doses of the drug were used worldwide, of which about 80% of Americans used a prescription. Ritalin is available as generic and commercial immediate-release medication (5, 10, and 20 mg come in methylphenidate hydrochloride strength) and continuous-release tablets (20 mg methylphenidate hydrochloride strength).