Let’s Start today in this podcast discussing one of the most common chronic health care issues in this country that is high blood pressure or hypertension and we’re going to be discussing probably the first medication generally prescribed to treat this condition, those of diuretics or what we call water pills.
To really get an understanding of how water pills work we really kind of have to get a close up view of what high blood pressure is. High blood pressure really is a result of our narrowing of blood vessels making the heart have to work harder forcing the heart to pump harder, and therefore generating a lot higher pressure to put fluid in blood through the heart through the blood vessels to circulate through the body. With that in mind most water pills work very much the same way they reduce the amount of fluid that the heart has to pump through the body has to pump out to the blood vessels, and therefore reduce the amount of pressure needed. To do just that there are three classes of water pillsthat we have and we used to treat high blood pressure and the first one is called the thiazide diuretics, now don’t worry about remembering the name you’ll probably hear hydrochlorthiazide if you have been prescribed that or you’ll see it with four specific letters HCTZ.
The thiazide diuretics work in the kidney and what they do is they promote the formation of urine by stimulating the kidney to release a specific substance and that substance is called sodium the substance, really is a mineral or what we call an electrolyte again not that important for you to remember, but remember this sodium is like a water magnet wherever sodium goes usually water will follow so the thiazide diuretics stimulate the kidney to release sodium into the urine and what occurs is water follows it therefore we get an increase in the amount of fluid urine formation and volume that you would urinate out.
So let’s recap what thiazide diuretics do, the thiazide diuretic , hydrochlorothiazide, being probably the more familiar one abbreviated by 4 letters HCTZ what they do is they grab ahold of sodium they stimulate sodium to be released by the kidney into the urine, the sodium being the water magnet, basically brings water and fluid with it into the urine so we get a greater volume of urine and therefore reduce the amount of fluid in the body, thereby reducing the workload on the heart having to have to contract and have a reduction in pressure so that the fluid can go from the heart into the blood vessels. However, there is also another substance that thiazide diuretics cause a loss of and that is potassium being a substance, a mineral what we also call again like sodium and electrolyte, is very important to the function of the body now that’s why it’s important to always have blood tests and your health care provider would probably give you a blood test very simple one that shows whether your blood Potassium levels are within normal range. Now, some people can take thiazide diuretics without having a change in their potassium levels, others there may be a slight change in their potassium levels which may you want to think about eating potassium rich foods green leafy vegetables, orange juice, bananas, fruits that have high amounts of potassium you’ll see in my story notes are my show notes a list of or a link to a list of high and rich potassium foods there are those people who will also lose potassium but a larger amount of it and therefore their blood levels of potassium do go below normal, not to worry we have potassium supplements that your health care provider will prescribe, and they come either in tablet or in packet powder form where you will simply reconstitute or take the packet in the powder put it in the specified amount of water mix it up and it will dissolve and you drink that.
The next class of water pills are also called loop diuretics, these are pretty potent, you may know it by the name furosemide. There are a few others, again the lists will be in my show notes and the entire episode will be transcribed so that you don’t have to worry if you don’t have a piece of paper or you’re not writing this down it will be there for you. The loop diuretics work basically the same way as the thiazide diuretics in that sodium is lost, potassium also is lost so and again with loop diuretics you need to have your health care provider will take a blood test to find out whether or not you have normal potassium levels and will prescribe, if needed, potassium supplements. Why they’re called loop diuretics is that they work in a specific point in the kidney where there is a specific area of the kidney where they work and they name it loop because there’s a loop in that area.
The third class of diuretics is called potassium sparing diuretics which obviously the name gives it away. These diuretics you do not lose as much potassium as the thiazide and loop diuretics where you need to have blood tests taken to find out your potassium blood levels to making sure that they are within normal limits, and if not supplements need to be taken. They work in the kidney, they do draw out sodium, sodium is the water magnet increasing the volume of urine and therefore reducing the amount of fluid the heart has to pump.
How are these usually prescribed? Well, they can be prescribed once a day or twice a day depending upon how your health care provider and your particular condition. The best time to take these medications, and I’m talking all three classes now, are usually in the morning early morning hours when you get up have breakfast, for those of you who may need a potassium dietary supplement orange juice bananas things to that nature would be something you would take. If you have to take it twice you may want to take it again in the morning and then midafternoon. What you don’t want to do is take these medications late at night, not unless you want to be getting up and interrupt your sleep going to the bathroom. So, the best way to do it at the best time to take it is if it’s once a day is early morning, if it’s twice a day, early morning, and midafternoon. You want to avoid taking it late or late afternoon or early evening and have your sleep interrupted. Overall, in all three classes of water pills they’re relatively safe medications there are a few common side effects that you want to be aware of and that if you experience you want to contact your health care provider just to let them know.
Some of the common side effects are headache and dizziness cramping dehydration now a lot of this may be due to the amount of fluid that you’re losing that your body isn’t accustomed to. You should, especially with dehydration, make sure that you drink a normal amount of fluids per day, now I so now it does sound a little strange here we’re losing fluid wanting to so that we can reduce our blood pressure in the workload of the heart, but you also must maintain the normal amount of body fluids as well, so make sure that your you’re drinking enough fluids daily fluids. You know, there’s a old adage from athletes, if you feel thirsty you’re already dehydrated that’s why athletes constantly drink even though they don’t feel thirsty small amounts of fluids throughout the day, might be something you want to consider. I want to bring up this point with the two categories of water pills thiazide and loop diuretics. If you know that you’re allergic to sulfa medications please let your provider know as well as your pharmacist, it’s important because you may not be able to take these two medications or these two classes of medications.
So let’s do a little bit of a recap we have three classes of water pills thiazide loop and potassium sparing. Basically, they all work at the same area, in the kidney, basically they work the same way they allow sodium to be excreted, sodium being the water magnet, it basically brings water with it the causing less fluid volume in the body the less the workload of the heart. The less the work the heart has to contract, and the less pressure needed for the heart to push fluid through into the narrow blood vessels. The overall side effects are headaches dizziness cramping and dehydration obviously it’s important to make sure that you drink enough water to maintain the normal amount of fluid in your body because you’re losing fluid through the diuretics. It’s important that you also know that any kind of allergies you have to medication any allergies to medication you need to make sure that both your health care provider and your pharmacist know. What they are best time to take these medications? Early morning and if you have to take it twice a day that would be midafternoon, what you do want to avoid is taking him later in the evening because you don’t want to have to wake up or have interrupted sleep going to the bathroom and urinating. So, I hope that answers some of your questions about water pills and I hope to have you come back next week at the same time where will be disgusting another type of medication used for high blood pressure which will be what we call ace inhibitors and ARBs.
References & Links
- Types of blood pressure medications. American Heart Association. https://www.heart.org/en/health-topics/high-blood-pressure/changes-you-can-make-to-manage-high-blood-pressure/types-of-blood-pressure-medications. Accessed July 12, 2021.
- Mann JFE. Choice of drug therapy in primary (essential) hypertension. https://www.uptodate.com/contents/search. Accessed June 25, 2019.
- Cifu AS, et al. Prevention, detection, evaluation and management of high blood pressure in adults. JAMA. 2017;18:2132.
- Brater DC, et al. Mechanism of action of diuretics. https://www.uptodate.com/contents/search. Accessed June 25, 2019.
- Drug record: Diuretics. National Institutes of Health. https://livertox.nlm.nih.gov/Diuretics.htm. Accessed June 25, 2019.
- Reboussin DM, et al. Systematic review for the 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA guideline for the prevention, detection, evaluation, and management of high blood pressure in adults: A report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. Circulation. 2018;138:e595.
- Aronson JK. Diuretics. In: Meyler’s Side Effects of Drugs. 16th ed. Amsterdam, Netherlands: Elsevier; 2016. https://www.clinicalkey.com. Accessed July 12, 2021.
- Whelton PK, et al. 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA guideline for the prevention, detection, evaluation, and management of high blood pressure in adults: A report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. Hypertension. 2018;71:e13.
Examples of thiazide diuretics taken by mouth include:
Examples of loop diuretics include:
- Bumetanide (Bumex)
- Ethacrynic acid (Edecrin)
- Furosemide (Lasix)
- Torsemide (Soaanz)
Examples of potassium-sparing diuretics include:
- Amiloride (Midamor)
- Eplerenone (Inspra)
- Spironolactone (Aldactone, Carospir)
- Triamterene (Dyrenium)
Link to Potassium Rich Food