According to Wikipedia, Methylphenidate (the active ingredient in Ritalin) was patented in 1954.
But it wasn't until several years after the compound's patent expired in 1967 that Ritalin- the brand-name version of methylphenidate- was manufactured by Ciba for the use in treating ADHD in children. Name brand Ritalin is now manufactured by Novartis.
Read more about ADHD medications HERE.
Ritalin has been on the market for quite some time now. It has been vigorously studied and researched throughout the years.
Previously, I posted a brief history of ADHD that you might be interested in:
The History of ADHD
Thanks for your question