Welcome back family! Hope you had a wonderful Father’s Day weekend with your loved ones and are ready for another Topic Tuesday post!
If you recall from last week, we talked a lot about some of the drugs used to help treat high blood pressure, including ACE-inhibitors, Angiotensin II receptor blockers, beta blockers, and aldosterone antagonists! Can you answer this week’s challenge question? Comment your answer down below:
What drug class (ACE-inhibitors, Angiotensin II receptor blockers, beta blockers, aldosterone antagonists) are the following medications?
A. Losartan = _______
B. Metoprolol = ______
C. Lisinopril = ________
D. Spironolactone = _________
This week, we keep the theme of discussing hypertension medications by discussing another very important drug class: Diuretics. Sometimes known as “water pills”, these medications help you lower the amount of salt/water (and blood pressure!) in your body by increasing the amount of times need to urinate.
As blood flows through the kidneys, it will contain salts, water, and wastes that the kidneys will take and filter before returning to the body. There are several channels throughout the nephron (functional unit of the kidney) that work to reabsorb things such as sodium, glucose, proteins, and water.
Diuretics will have their effect by blocking different channels in your kidney that reabsorb salts and water. By blocking the “reabsorber” channels, these substances will remain in your urine instead of returning to your blood, and will go on to be removed from your body when you use the bathroom.
There are several types of diuretic, each with a unique function, effect, and potential side effects. A good summary is provided by this article from the Cleveland Clinic -
1. Thiazide diuretics (ie. hydrochlorothiazide, chlorthalidone)
Thiazides function by blocking a sodium/chloride co-transporter causing increased salt and water to stay in the urine. Their main benefit is seen in patients with hypertension as they allow a moderate reduction in body volume.
One other unique benefit of thiazides can be seen in patients with recurrent calcium kidney stones. This is because although thiazides cause a loss of salt/water, they increase the reabsorption of calcium from the urine back into the body -> Less calcium in urine means a lower risk of them hardening into kidney stones.
Main side effects of thiazides include dizziness, headache, hair loss, muscle weakness (due to decreased potassium).
2. Loop diuretics (ie. furesomide (lasix), bumetanide)
Loop diuretics function by blocking a large sodium/potassium/chloride channel causing MASSIVE loss of salt and water from urine. Loops are much more powerful than other diuretics and can cause a very significant reduction in volume from the body.
For this reason, they are are less commonly used in patients with hypertension compared to thiazides. Their main use is for patients with congestive heart failure, where a build up of fluid that can’t be pumped by the heart causes many of the symptoms (difficulty breathing from fluid in lungs, swelling in feet.) Loop diuretics will help remove fluid from these patients and improve how they feel!
Main side effects of loop diuretics include dizziness, headache, hearing loss, muscle weakness (due to decreased potassium).
3. Potassium-sparing diuretics (triamterene, amiloride)
If you noticed from loop/thiazides, one main side effect of these drugs is that they may cause a drop in potassium from the body with eventual muscle weakness/cramping. While a mild drop in potassium may be tolerated by many patients, some susceptible individuals may be at risk for more serious side effects from low potassium, including heart arrhythmia.
Potassium-sparing diuretics may be a viable alternative for patients that allow a reduction in salt/water from the body without sacrificing potassium. They work by interfering with potassium channels in the later part of the kidney and antagonizing the effects of aldosterone (which normally increases potassium removal form the body.)
Main side effects of potassium-sparing diuretics include hyperkalemia (too much potassium!), headache, and dizziness.
And that wraps up this week’s session! We hope to see you next week for the last installment of our medication series, where we will discuss some less commonly used drugs for hypertension and how they work! Thank you for tuning in and until next time, remember to always Think Aorta.
Adham Ahmed, M3
CUNY School of Medicine