text: You should follow your doctor's and pharmacist's directions. SR and XL are both forms of extended release tablets but they have different durations and taking them at the wrong times could put too much drug in your system for a while and then leave you high and dry. Often docs will prescribe SR two-three times a day versus XL once daily (or maybe in your case your doc wants you to take it twice daily). XL has a longer extended release.\n\nAlways check with a pharmacist if you have questions before taking a medicine, but it's probably safest to follow the instructions on the label.