My dr has replaced the atenolol 25 mg once a day at night( not available) to the metoprolol tartrate to 25mg. twice a day/ why the increase?

Not sure: Since metoprolol is the generic of Atenolol, and should be equivalent, I am not sure why your doctor increase the number of pills from one a day to two a day. I would suggest you talk to the physician who prescribed the medication to clarify the directions. I do not want you to develop side effects, so talk to you doctor. Good luck

Dose: These are equivalent and not an increase in dose . Good Luck