While you already have your answer, I thought I’d share this for anyone wanting to know a bit more about how Concerta works. The pills themselves use an osmotic-controlled release oral delivery system where part of the dose is given immediately and the rest is slowly given as the drug gets squeezed out a little hole (that’s drilled out by lasers!) by osmotic pressure. It’s really cool stuff and makes it quite different to Ritalin IR in how it feels and works.
That release is quite out of date. See this issue