Hi & Welcome to HCM. Incomplete data like age, gender, names of the prescribed medications for high BP, Atrial fibrillation, etc. not mentioned so it becomes difficult to give the opinion. Probenecid can interfere with most of the BP lowering medications, blood thinners like Aspirin, etc. Taken along with Aspirin, it blocks its elimination from the body and thus increases the risk of bleeding because of the Aspiring toxicity. Losartan (a BP lowering medicine) is found to be effective in patients suffering from gout as it is known to reduce the high serum uric acid, hence it can be a better choice. Hence, you are advised to consult your treating doctor to review the prescription and to prescribe a safer medication for the treatment of gout without altering the efficacy of other medications taken for high BP and Atrial fibrillation.