Attention deficit hyperactivity disorder (ADHD, similar to hyperkinetic disorder in the ICD-10) is a psychiatric disorder of the neurodevelopmental type in which there are significant problems of attention and/or hyperactivity and acting impulsively that are not appropriate for a person's age. These symptoms must begin by age six to twelve and be present for more than six months for a diagnosis to be made. In school-aged individuals the lack of focus may result in poor school performance.
Despite being the most commonly studied and diagnosed psychiatric disorder in children and adolescents, the cause in the majority of cases is unknown. It affects about 6 to 7 percent of children when diagnosed via the DSM-IV criteria and 1 to 2 percent when diagnosed via the ICD-10 criteria. Rates are similar between countries and depend mostly on how it is diagnosed. ADHD is approximately three times more frequent in boys than in girls. About 30 to 50 percent of people diagnosed in childhood continue to have symptoms into adulthood and between 2 and 5 percent of adults have the condition. The condition can be difficult to tell apart from other disorders as well as that of high normal activity.
A prodrug is a medication that is initially administered to the body in an inactive (or less than fully active) form, and then becomes converted to its active form through the normal metabolic processes of the body.
A prodrug serves as a type of precursor to the intended drug. Prodrugs can be used to improve how the intended drug is absorbed, distributed, metabolized and excreted (ADME). Prodrugs are often designed to improve oral bioavailability in cases where the intended drug is poorly absorbed through the gastrointestinal tract. A prodrug may also be used to improve how selectively the intended drug interacts with cells or processes that are not its intended target. This reduces the adverse or unintended effects of the intended drug, especially important in treatments like chemotherapy, which can have severe unintended and undesirable side effects.