Effects of ARBs on potassium levels?

Question

Angiotensin II receptor blockers (ARBs) are commonly used to treat hypertension. One of the side effects of these drugs is to raise serum potassium levels. This occurs because ARBs block the effects of angiotensin II on receptors, which leads to reduced aldosterone production. Aldosterone causes retention of sodium and excretion of potassium, thereby lowering serum potassium levels. My question is whether this effect is immediate or delayed. For example, if a person begins taking an ARB daily, will its effect on potassium levels be the same on day 1 as it will be on day 30? Assume normal kidney function and no other drugs. If the particular ARB matters, consider losartan.

Answer 1

The answer to your question really depends upon the specific drug you are looking at to block Angiotensin 2. You'd have to look up a dose response study for each specific drug which should tell you it's bioavailability, that is how much of the drug actually reaches the circulation, as well as it's pharmacokinetics. There isn't a simple answer to your question. Great question, just not a simple one and one that needs to be answered in the context of each specific drug/class of drug. The quicker it can get into the circulation, the quicker it can act. Though it's potency is dependent upon many things. When you eat a cookie, you can expect the glucose to enter your blood within 15 minutes or so.