How does ritalin (methylphenidate) work at the chemical level, in hyperactive children?

Increased inhibition: Hyperactivity in add occurs because inhibitory brain systems are "under active." Ritalin (methylphenidate) appears to work by increasing this inhibitory signal and thus decreasing hyperactivity.

Via two chemicals: Ritalin (methylphenidate) blocks the chemicals Dopamine and noreadrenaline from being taken up into neurones (which is the way these chemicals are cleared) hence making them more available for use and helping to improve attention and concentration.

Increase transmitter: ADHD with hyperactivity is related to a low amount of Dopamine and Nor epinephrin in the brain. Stimulants such as Ritalin (methylphenidate) and amphetamines work by increasing the brain levels of these neurotransmittersm restirubg a balance.