Difference between sr and xr?it's not clear in many references, i know both of them will be released gradually for goals.2) ritalin (methylphenidate) usual adult dose?

Delayed release Meds: The difference between the sr and xr preparations is how the drug is packaged for delayed delivery. Both are delayed released preparation and provide a uniform delivery of medication through the day. Usually the dose is 1to 1 for methylphenidate. The delayed release form doesn't have a peak or jolt that certain patients need.

SR, XR=Time Release: Sustained release and extended release signify preparations of a medication that employ some kind of time-release technology (e.g., slowly dissolving capsule, medication embedding in a special matrix) and contrast with "immediate release" (ir). Ir forms often require multiple doses a day, while sr and xr may require only one or two - best to check the dosing schedule for each particular prep.