losartan potassium
Meaning of losartan potassium: Blocking the receptor rather than the enzyme that builds the hormone is what spares this drug class the dry cough of its predecessor.
Definition of losartan potassium
Losartan potassium is a medication that lowers blood pressure by blocking the receptor through which angiotensin II acts. Angiotensin II is a hormone that tightens blood vessels and prompts the body to hold on to salt and water. With its receptor occupied, vessels relax and less fluid is retained, so pressure falls. It belongs to the class called angiotensin receptor blockers.
How does it differ from an ACE inhibitor?
| Angiotensin receptor blocker | ACE inhibitor | |
|---|---|---|
| Where it acts | At the receptor the hormone binds | At the enzyme that produces the hormone |
| Effect on other signals | Leaves them alone | Also blocks breakdown of an unrelated signaling molecule |
| Dry cough | Uncommon | A well recognized reason people stop the drug |
The two classes lower pressure by interrupting the same hormone system at different points, and their blood pressure effects are broadly comparable. The cough is the practical distinction. The enzyme blocked by the older class also disposes of a molecule called bradykinin, which accumulates and irritates the airway, and blocking the receptor instead sidesteps that route entirely.
What is it used for besides blood pressure?
Two things in particular. In people with type 2 diabetes who are losing protein into the urine, the drug reduces the pressure inside the kidney's filtering units and slows the decline in kidney function, a benefit that goes beyond what the drop in arm cuff pressure alone would predict. It is also used where the left side of the heart has thickened against years of raised pressure, since easing the load allows some of that thickening to reverse. Losartan additionally increases the amount of uric acid passed in the urine, a small effect not shared by others in its class.
What does the potassium in the name mean?
It refers to the salt form the drug is supplied in, a manufacturing detail rather than an added mineral, and the quantity involved is negligible. The confusion is understandable, though, because the drug does affect potassium levels by a completely different route. Blocking angiotensin II reduces release of aldosterone, the hormone that instructs the kidney to shed potassium, so less is excreted and the level in the blood tends to rise. That effect is why blood chemistry is monitored on this class of drug, particularly alongside other treatments for high blood pressure that act the same way.
Also known as
Used in a sentence
Losartan potassium was prescribed to manage the patient's high blood pressure.
Good to know
Losartan potassium blocks the action of angiotensin II rather than reducing its production, a mechanism distinct from a related class of blood pressure medications that instead block the enzyme generating the hormone.