Feb 3, 2023
Diuretics Pharmacology Mnemonics
From Glomerulus to Collecting Duct, I give you some easy ways to remember and sort the diuretics.
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Auto Generated Transcript:
Welcome to the Memorizing Pharmacology podcast. I’m Tony Guerra, pharmacist and author of the Memorizing Pharmacology book series, bringing you mnemonics, cases, and advice for succeeding in Pharmacology. Sign up for the email list at memorizingfarm.com to get your free suffixes cheat sheet or find our mobile-friendly self-paced online pharmacology review course at residency.teachable.com forward slash P forward slash Melbourne. Let’s get started with the show.
Okay, today we’re going to go over diuretic pharmacology mnemonics and where we’re going to start actually is just a little brief review of you know what happens with urine formation and there are four words you really need to know. So filtration happens at the glomerulus and glomerulus just means like bundle of string or because it’s all kind of convoluted. Reabsorption which happens at the renal tubules so to the paratubular or renal capillary so when you’re looking at reabsorption okay what’s happening is that you are getting it to come back okay so you’re getting that fluid whatever it is to resorb into the capillaries whereas secretion is the opposite so you can kind of see the arrows here where secretion is the peritubular or renal capillaries going into the collecting duct which will eventually result in number four which is excretion from the body.
But this should look weird to you at some point in your anatomy class you learned that an artery went to a little arterial which went to a smaller capillary which went to a little venial which went to veins but Bowman’s capsule actually has an efferent an afferent arteriole so it goes arterial capillary arteriole what that does is it creates a really high pressure system much like a garden hose and the way we’re going to learn this because that pressure is so high at the one part that means the pressure at the end of that hose is much lower.
So I don’t know if you remember from if you’re in the United States you learned the United States generally in four regions you learn the west and maybe you broke that up into southwest and west then the Midwest then Southeast and then the Northeast so we’re going to do the same thing here because those regions are different when we talk about the Nephron. So our western region is going to be the proximal convoluted tubule so proximal just means close to something so I’m in close proximity to you so proximal to the glomerulus and that really high pressure system that’s going to be one. The Carbonic and hydrase Inhibitors like acetazolamide and which is Diamox and two, the osmotic diuretic so Mannitol which is osmetrol.
Then we’re going to kind of go to the Midwest where we’re going to see the ascending Loop of henle or the ascending limb of the loop of henle and that’s our Loop Diuretics now. The big thing here is going to be hypokalemia and we’ll talk about how we deal with that in a later slide but this is furosemide which is Lasix torsomide demidex and bumetanide which is bumex.
Then we move on to what would probably be the Northeast which is the distal convoluted tubule and really the early part of the distal convoluted tubule so. The thiazides will also cause hypokalemia so this Midwest and Northeast this kind of middle of the Nephron is causing hypokalemia this is going to be important because later we’re going to see the opposite. And this is Hydrochlorothiazide which is diazide if you combine it with triamterene and then chlorthalidone which is thalatone though probably couldn’t find the brand name if we wanted to.
And then, last one is the DCT or collecting duct so these are number five which is potassium sparing group okay. So again this is at DCT right at collecting duct so towards end of that distal convoluted tubule and we have hyperkalemia so later on we’ll see that we can pair these together. And I’ve seen a couple mnemonics for this but I like mine better I like use spare for sparing so it’s spironolactone we use SP which aldactone amyloride which metamore triamterene we have take R which second letter it’s not ideal but again I think spare better mnemonic for dyrenium then eplerenone which Inspira eplerenone spironolactone work same way amyloride trampoline work same way see later.
Alright, I always feel like I’m defending mnemonics against those who say that you’re not understanding it, you’re just memorizing it, and you want to really want understand it well I’m not saying don’t understand it. Think that it’s a lot easier to understand things if I have the desk on the right than the desk on the left. So with mnemonics, I’m just trying to make it so that you’re not cluttered so that you can kind of clearly understand a concept, move on to the next. So to me, pharmacology without mnemonics is the desk with all that junk on it and pharmacology with mnemonics is the nice clean desk on the right.
So our mnemonic that we use to as we kind of go through these medications and we’ll look at some other pieces of it that can help us as well but I am a considerate health professional and that considerate is really for considerations and contraindications but being empathetic to what it is that the patient has right now and you can see what I’m doing there getting our ducks in a row all right we’ll put our generic name then brand name first and he stems we’ll try to underline those and then again I is for indication M for mechanism of action which again you can just say the drug class so what is the mechanism of action of acetazolamide well you can just say it is a Carbonic anhydrase inhibitor okay that is the mechanism of action now your instructor probably wants it is a Carbonic anhydrous inhibitor that does blank that’s probably what they want adverse effects are the A considerations are the C and then how can we help the patient best take their medication is H.
So let’s move first to acetozolamide which is Diamox. It is for intracranial hypertension intraocular pressure hopefully those two intras help you remember it and then also altitude sickness so I have a home in Arizona and although it’s like bright can’t afford Flagstaff now the way that things have gone up but I think of Arizona mind instead of acetazolamide so this is actually a picture of Humphrey’s Peak which is the tallest mountain in Arizona and you would get altitude sickness if you went all the way up there so I also changed Arizona mide instead of the amide amide to m-e-y-e-d because of that intraocular pressure and then the M for Mountain so I got it all in there.
The mechanism of action is that it is a Carbonic anhydrase inhibitor which means that we retain carbonic acid since there is a road there would probably be a car on there all right see what I did there all right. And so what we’re going to have is this kind of leads to our adverse effect metabolic acidosis because of that carbonic acid that we’re retaining. So what are our considerations? Well, we want to watch out for that acid base balance and really renal disease would be a real problem with using acetazolamide and you know how can we help them take it? We want to make sure we have Labs on them and then watching that intraocular pressure as well okay.
Alright, let’s go on to our next one again we’re still in that West Coast we’re still at that proximal convoluted tubule proximal to the glomerulus with Mannitol which is osmotrol. And the nice thing about that and acetazolamide is that it really it’s very similar indications intracranial hypertension intraocular pressure it’s an osmotic you might recognize Mannitol from sorbitol they look really same there’s sugar alcohols they look really similar okay. And the big issue though are going to be those electrolyte imbalances and then because it creates so much diuresis we could become hypovolemic that is too little volume.
So our contraindications anytime we have electrolyte imbalances generally something like congestive heart failure is a real concern and then dehydration certainly if we’re going to have too little volume and we’re going to use our Labs as our way of making sure that things are on the up and up. So I just have a collision here a man who has head trauma or intracranial issue and so if you want to you can look at NIT in Mannitol mix letters around make I T remind you intra cranial intraocular pressure furosemide or Lasix P furiously because this creates also lot diuresis but certainly not as much as Mannitol but more than Hydrochlorothiazide. And so we’ve moved from west coast to midwest okay, so the Midwest has a couple of different issues with it. I live in the Midwest but I'm talking about in terms of our mnemonic here. So indications notice that we would use this for CHF as opposed to something like Hydrochlorothiazide which doesn't produce as much diuresis which would be for hypertension a lesser condition. So CHF edema that's certainly why I would use furosemide. It blocks sodium and water resorption in the ascending Loop of henle so again that's kind of our Midwest portion and so because of that we're going to get hyponatremia that is we lose that sodium and also hypokalemia and that is that middle section where both the ascending Loop of Henley drugs and that distal convoluted tubule which we'll talk about in a second both of those guys are hypokalemia. We'll get to the Southeastern section where we will talk about hyperkalemia okay.
So when you take away that much fluid though it's likely you could get orthostatic hypotension now the ototoxicity and nephrotoxicity are part of furosemide but it's a little bit tough it's like how do you remember that those are are part of it and so I I've got a picture of tinnitus here or tinnitus as some people say it and that's that kind of ringing in the ears the buzzing for some people it's a roaring or a clicking or a hissing or a humming but this is that damaged nerve cell that's causing this really uncomfortable ringing in the ears okay.
So ototoxicity that's how it would probably present um and then so you know what considerations we have well we don't want to give something that causes hyponatremia to somebody who is hyponatremic already or hypokalemic already and then certainly with renal disease if we're going to have these kinds of electrolyte imbalances we really want to be careful there. So what do we do well we make sure the labs are again where we want to see them and then be really careful with ototoxic drugs nephrotoxic drugs because we don't want to have an additive effect.
Alright, Hydrochlorothiazide so again the big contrast here as we move from that Midwest to the Northeast here is that we're treating hypertension level issues rather than CHF level. So this is really first thing first line against hypertension and then edema certainly. So the mechanism now we are blocking sodium and water resorption but because we're further away from that efferent and afferent arteriole when we block that sodium and water resorption we're not doing as much or we're not causing as much diuresis because we're further away to the right okay.
And again distal is the opposite of proximal so proximal is close to something distal is distant from it. So the adverse effect is hypokalemia but also hyperuricemia so we're still in that hypokalemia Zone in the middle but the hyperuricemia means I increase uric acid uric acid is bad for what condition yeah gout exactly there's some misunderstanding as to what sulfa allergy really means when you talk about sulfa and it's because many people that are talking about sulf haven't taken organic chemistry and certainly not taught it but sulfa is talking about this group here where you have an R Group.
And so it doesn't really matter what's going on to the left of this s here but these two oxygens bonded to the s in this way or the sulfur in this way also bonded to a nitrogen which also has two R groups which happen to be hydrogens in this case but you notice Hydrochlorothiazide and furosemide both have this sulfa group. And if you were to look at acetazolamide you'd see the same thing. So unfortunately, you can't generally see the chemical formula in this way but if you could, you could very easily say okay that’s a sulfa drug right. So the reason I point this out is that you will notice that acetozolamide, furosamide and Hydrochlorothiazide none of them have the word sulfa in it okay like sulfa methoxazole an antibiotic you learn about. So just because it doesn’t have sulfa doesn’t mean it can’t be a sulfa drug. Sulfa is pointing to this moiety which is on the organic chemistry group and then so again it’s the labs that we really want to watch out for that hypokalemia hyperuricemia.
Alright, so here’s the mnemonic for the potassium sparing and I just put these all together. Spironolactone because it does block aldosterone you will see something like gynecomastia but what I really want to kind of take away from this section is that we like to pair these potassium sparing drugs with the hypokalemic drugs. So again those hypokalemic drugs were furosemide okay so spironolactone which blocks aldosterone would pair with furosemide and so what eplerone which also blocks aldosterone and that pairs with furosemide.
How does spironolactone work well oh you just think about what aldosterone does. So aldosterone holds onto salt or sodium chloride or sodium and water to increase our blood pressure when our blood pressure goes too low. So if we’re going to block that okay we’re going to block it now we’re going to lose sodium okay and now we’re going to lose water but because we are so far away from that glomerulus that high pressure system the amount of diuresis is very low.
So the actual purpose of these drugs is generally to maintain potassium homeostasis or to make sure that the hypokalemia gets x’d out by this hyperkalemia. So when you talk about what are the side effects of a potassium sparing diuretic well hyperkalemia would be the one that comes to mind. So again the spare mnemonic is SP for spironolactone, A for amyloride, R for trianterine and E for a plurinone. The spironolactone and the plearnone both go with furosemide, the amyloid and triamterene pair so well with Hydrochlorothiazide that there are actually medications that have them paired together.
So amyloride with Hydrochlorothiazide becomes modular edict and triamterene with hydrochlorothiaz becomes diazide. Last point I want to make is about potassium supplementation itself so I just got two pictures here IV bag potassium slow sign on the curve so I remember going up the mountains you know in Colorado as we were kind of going up to Pike’s Peak and I assure you it is terrifying if you’re the driver and you go very slow.
So potassium supplementation go very slow uh don’t even think about doing something like crushing tablets or something like that to make things you know go faster everything must be very slow when you go with potassium supplementation alright as always this information is provided to you for informational purposes only not intended to provide and should not be relied upon for medical or other advice if you’ve got a medical condition talk to a medical professional.
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Like to learn more?
Find my book here: https://geni.us/iA22iZ
and subscribe to YouTube Channel TonyPharmD here: https://www.youtube.com/c/tonypharmd
Here is the Link to my Pharmacy Residency Courses: residency.teachable.com