Unlawful possession is punishable by six-month prison sentence and distribution by a 14-year sentence. In Australia, methylphenidate is a Schedule 8 controlled substance. Such drugs must be kept in a lockable safe until dispensed and possession without prescription is punishable by fines and imprisonment. In Russia, methylphenidate is a List I controlled psychotropic substance without recognized medical value. The Constant Committee for Drug Control of the Russian Ministry of Health has put methylphenidate and its derivatives on the National List of Narcotics, Psychotropic Substances and Their Precursors and the Government banned methylphenidate for any use on 25 October 2014. In Sweden, methylphenidate is a List II controlled substance with recognized medical value. Possession without a prescription is punishable by up to three years in prison. In France, methylphenidate is covered by the "narcotics" schedule, prescription and distribution conditions are restricted with hospital-only prescription for the initial treatment and yearly consultations. In India, methylphenidate is a schedule X drug and is controlled by the Drugs and Cosmetics Rule, 1945. It is dispensed only by physicians prescription. Legally, 2 grams of methylphenidate are classified as a small quantity, and 50 grams as a large or commercial quantity. In Hong Kong, methylphenidate is controlled under the schedule 1 of the Dangerous Drugs Ordinance (Cap. 134). Controversy
Methylphenidate has been the subject of controversy in relation to its use in the treatment of ADHD. The prescription of psychostimulant medication to children to reduce ADHD symptoms has been a major point of criticism.
Ritalin SR), and 8–12 hours for extended release (i.e. Concerta). The half-life of methylphenidate is 2–3 hours, depending on the individual. The peak plasma time is achieved at about 2 hours. Methylphenidate has a low plasma protein binding of 10-33% and a volume of distribution of 2.65 L/kg.Dextromethylphenidate is much more bioavailable than levomethylphenidate when administered orally, and is primarily responsible for the psychoactivity of racemic methylphenidate.The oral bioavailability and speed of absorption for immediate-release methylphenidate is increased when administered with a meal. The effects of a high fat meal on the observed Cmax differ between some extended release formulations, with combined IR/ER and OROS formulations showing reduced Cmax levels while liquid-based extended release formulations showed increased Cmax levels when administered with a high fat meal, according to some researchers. A 2003 study, however, showed no difference between a high fat meal administration and a fasting administration of oral methylphenidate.Methylphenidate is metabolized into ritalinic acid by CES1A1, enzymes in the liver. Dextromethylphenidate is selectively metabolized at a slower rate than levomethylphenidate. 97% of the metabolised drug is excreted in the urine, and between 1 and 3% is excreted in the faeces. A small amount, less than 1%, of the drug is excreted in the urine in its unchanged form. Chemistry
Four isomers of methylphenidate are possible, since the molecule has two chiral centers. One pair of threo isomers and one pair of erythro are distinguished, from which primarily d-threo-methylphenidate exhibits the pharmacologically desired effects.