The long acting form ( Ritalin SR) comes only in a 20 mg tablet. It is designed to slowly release its contents from a series of "microchannels", and the tablet can not be cut. This dosage form is quite variable, working well for some people but poorly for others. It may be worth trying if a child on Ritalin is very resistant to taking medication at school. It tends to start acting more slowly than regular Ritalin, often taking 1.5 hours to start working. For this reason, it is often given with a small dose of regular Ritalin in the morning to provide initial coverage. Ritalin SR peaks at approximately 4.5 hours from the time it is administered.
It is not uncommon to have parents report a "rebound hyperactivity" in the
late afternoon as the long acting Ritalin wears off.