A generic drug is a medicine with the same active ingredient, strength and dose form as a branded medicine, sold under its chemical name once the patent has ended.
Generics must meet the same standards for quality and for how much of the active ingredient reaches the bloodstream. They usually cost less because the original research costs are not repeated.
Long-acting ADHD medicines need extra care here. Different brands of the same long-acting medicine can release it on different timings across the day, even with the same active ingredient. Switching brands can change how your day feels, so long-acting methylphenidate is usually specified by brand rather than by generic name.
If your pharmacy offers a different brand, ask whether the release profile is the same before you switch.