<qa>  What is the amount of imatinib mesylate you take each morning andDuring the study you will take 400 mg of imatinib mesylate by mouth 2 times a day 800 mg a day total. Imatinib mesylate should be taken each morning and evening with a large glass of water. You may be given a pill diary to write down when day and time you take the drug. You may also write in the diary any side effects you may experience. You may bring the diary, any unused tablets, and empty bottles of imatinib mesylate with you to every visit to the study doctor. Any unused supplies must be returned at the end of the study. 