Atenolol belongs to the group of medicines called beta-blockers. Atenolol reduces the heart rate and the force of heart muscle contraction and lowers blood pressure, by blocking the action of the nervous system on the heart. It works by stopping the reabsorption of salts and water from the kidneys into the bloodstream. Amiloride is also a diuretic, but it works in a different way. It blocks salt reabsorption from the kidneys, but also stops potassium from being lost.
Potassium is vital for the normal operation of the nervous system, muscles and the kidneys.
It is very important to take medicines as often as your doctor has told you to, even if you do not feel ill. This is because heart and blood pressure problems, if not treated, can get progressively worse. It is also important to follow any lifestyle instructions that your doctor has given to you, like trying to give up smoking, reducing your weight, doing more exercise and eating a healthy diet.