Pharmacology, part 41: Renal Medications - Diuretics

September 15, 2021 Updated: September 23, 2021 5 min read

Full Transcript

All right. In this video, we are going to talk about diuretics, and we're going to start off by talking about loop diuretics.

The key medication that falls within this class is furosemide or brand name, Lasix. This is a very important medication to know. You will administer it all the time in the hospital. In addition, chances are you're probably going to get questions about furosemide on your nursing exams.

So furosemide is used to treat conditions such as pulmonary edema, edema related to heart failure, liver disease, as well as kidney disease. In addition, it can be used for hypertension.

It works by blocking the reabsorption of sodium, chloride, and water at the ascending loop of Henle. It also causes increased excretion of potassium, magnesium, and calcium as well. So it does all of these things pretty quickly. It causes rapid dieresis.

So some of the side effects you can kind of guess based on the mode of action. Because we're getting rid of all of this fluid very, very quickly, it places the patient at risk for hypotension as well as dehydration, and because we're getting rid of all of these electrolytes as well, it places the patient at risk for key electrolyte imbalances, which include hyponatremia as well as hypokalemia. And any time we have an imbalance with potassium, whether that's hyperkalemia or hypokalemia, it places the patient at risk for life-threatening dysrhythmias. So we're definitely going to want to keep an eye on their potassium levels, as well as the other electrolytes when a patient is on furosemide.

Other side effects include autotoxicity. So you definitely want to assess your patient and ask them if they have had any hearing loss or if they have any tinnitus or other symptoms of autotoxicity. Other side effects include hyperglycemia, as well as a rash.

In terms of key teaching points, if we can administer this medication prior to 5:00 PM, we want to do so, because administering furosemide is going to cause the patient to pee a lot, and we don't really want to keep them up all night peeing. So if we can give it to them during the day, that's definitely going to be better. We're going to administer furosemide slowly, so we're not going to just slam it into the patient. We're going to give it at a rate of 20 milligrams per minute. We're going to weigh our patients daily, monitor their Is and Os, and also monitor their electrolyte levels, which is very important.

And then we want to encourage our patient to increase their intake of potassium-rich foods because of the risk of hypokalemia. So foods that are high in potassium include dark leafy greens, potatoes, cantaloupe, tomatoes, avocado, as well as other foods.

And then the way I remember this medication is if you look at the word furosemide, it starts with that F-U-R. And I remember that furosemide furiously gets rid of excess water.

All right. Now let's talk about thiazide diuretics. So the medication that falls within this class to know is hydrochlorothiazide.

Hydrochlorothiazide is used to treat conditions such as hypertension, often in conjunction with other antihypertensive medications. It's also used to treat edema related to heart failure, liver disease, or kidney disease.

The mode of action of hydrochlorothiazide is to block the reabsorption of sodium chloride and water at the distal convoluted tubule. It also causes increased excretion of other electrolytes just like furosemide, so it will cause increased excretion of potassium, calcium, as well as magnesium.

So in terms of side effects, key side effects include dehydration, because again, any time we have a diuretic, that's going to be a key risk factor. Also, hypokalemia is a key side effect, as well as hyponatremia because we're getting rid of those electrolytes.

So some of the key points in teaching are going to be the same as what we saw with furosemide. So we're going to want to administer this diuretic during the day if possible so that the patient isn't up all night peeing. We're going to want to weigh the patient daily, monitor their Is and Os, and monitor their electrolyte levels. And then we're going to want to encourage them to consume foods that are high in potassium because of that key side effect of hypokalemia. So we talked about those foods when we were talking about furosemide, so you just want to provide that education to your patient.

In terms of my little trick for remembering this medication, if you look at the word hydrochlorothiazide, it contains the word hydro for water and chloro, which is part of sodium chloride. So hydrochlorothiazide gets rid of water, hydro, and sodium chloride.

All right. Let's now talk about a potassium-sparing diuretic, which is spironolactone.

Spironolactone can be used for heart failure, as well as hypertension. It is contraindicated in patients who have severe kidney failure.

Its mode of action is to block aldosterone, which promotes the excretion of sodium and water, but the retention of potassium.

So key side effects include hyperkalemia because we are retaining that potassium. Other side effects include amenorrhea, which is lack of menstruation, as well as gynecomastia and impotence.

In terms of key administration points, you want to monitor your patient's potassium levels during therapy because of the risk for hyperkalemia, and you want to tell your patient to avoid salt substitutes because salt substitutes are high in potassium.

The way I remember this medication, if you look at how it's spelled, it's spelled S-P-I-R, so I think spironolactone will improve your spirits because you won't lack potassium. And that helps me to remember that this medication allows for retention of potassium.


All right. So let's finally talk about an osmotic diuretic, which is mannitol.

So mannitol is used for edema, as well as increased intracranial pressure. It's also used for increased intraocular pressure.

It works by increasing the serum, osmolality, which draws fluid from the intracellular space into the interstitial space, as well as into the plasma or the bloodstream.

So side effects of this medication can include pulmonary edema as well as heart failure. Because we're bringing all of this fluid back into the bloodstream, it can really overwhelm the lungs and the heart. Other side effects include renal failure, dehydration, as well as electrolyte imbalances, particularly with sodium and potassium, and then possible phlebitis.

In terms of key administration points, we're going to want to monitor our patient's weight, monitor their Is and Os, as well as their electrolyte levels. We also want to make sure we're bringing their intracranial pressure or intraocular pressure back into the expected range.

So the expected range for ICP is between 10 and 15 mmHg, and the expected range for IOP is between 10 and 21 mmHg.

The way I remember this medication is that I had a headache due to increased ICP. I took mannitol, and man, it all went away. So hopefully that's helpful for you.

We will be back with key medications for the reproductive system. Thanks so much for watching.


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