I agree with your doctor. Both medicines in Olmezest AM, olmesartan and amlodipine, do not cause increased frequency of micturition. Given your father s age, an enlarged prostrate (prostatic hypertrophy) is a likely cause. An ultrasonograph will reveal information about it which will help doctor in diagnosing the condition. If he has an enlarged prostate, it can be initially treated with medicines which will bring relief. In the meantime, ask your father to drink plenty of fluids during first part of day and less in the evening and just prior to going to bed. I hope this answer is helpful.