WEBVTT 00:00:07.880 --> 00:00:10.759 You're in the bay. Once you get over to the bed, 00:00:10.919 --> 00:00:13.560 we'll give you the story. Everything's going 00:00:13.560 --> 00:00:17.339 to happen super fast. Welcome to the emergency 00:00:17.339 --> 00:00:46.420 room. Imagine a microscopic fortress. The bacteria 00:00:46.420 --> 00:00:49.100 inside are just constantly working. Nonstop. 00:00:49.359 --> 00:00:51.960 They're snapping these chemical Lego bricks together 00:00:51.960 --> 00:00:55.520 to build a thick, impenetrable wall. And that 00:00:55.520 --> 00:00:57.840 wall is their only defense against the harsh 00:00:57.840 --> 00:01:00.000 environment and obviously against our immune 00:01:00.000 --> 00:01:02.719 system. Exactly. So today we are looking at the 00:01:02.719 --> 00:01:05.120 ultimate biological wrecking ball designed to 00:01:05.120 --> 00:01:07.879 just smash those bricks. We are taking a deep 00:01:07.879 --> 00:01:10.739 dive into an absolute heavy hitter antibiotic, 00:01:11.500 --> 00:01:14.859 vancomycin. Or you might see it under the brand 00:01:14.859 --> 00:01:18.870 name. Van Cosen. Right. Van Cosen. And for you, 00:01:18.870 --> 00:01:20.670 whether you're trying to master critical care 00:01:20.670 --> 00:01:22.870 pharmacology or you're just endlessly fascinated 00:01:22.870 --> 00:01:25.609 by medical science, we are channeling our inner 00:01:25.609 --> 00:01:27.909 elite critical care pharmacists today. Yes, we 00:01:27.909 --> 00:01:30.370 are. We're aggressively applying the 80 -20 Pareto 00:01:30.370 --> 00:01:33.189 principle to a massive stack of clinical data 00:01:33.189 --> 00:01:35.469 because we want to filter out the noise and focus 00:01:35.469 --> 00:01:38.170 only on the highest yield clinical facts, the 00:01:38.170 --> 00:01:41.430 nursing interventions and the exam relevant pearls 00:01:41.430 --> 00:01:43.930 needed to master this drug. It really is a high 00:01:43.930 --> 00:01:47.459 wire act. this one. I mean, vancomycin is a cornerstone 00:01:47.459 --> 00:01:50.239 of critical care medicine. But the line between 00:01:50.239 --> 00:01:52.900 saving a patient from a lethal infection and 00:01:52.900 --> 00:01:56.439 causing severe permanent toxicity is razor thin. 00:01:56.459 --> 00:01:59.239 Yeah. You can't just memorize a list of side 00:01:59.239 --> 00:02:01.519 effects here. You have to understand the underlying 00:02:01.519 --> 00:02:05.120 physical mechanisms because, well, the way it 00:02:05.120 --> 00:02:07.439 behaves in the human body is entirely dictated 00:02:07.439 --> 00:02:10.240 by how it attacks that bacterial wall. OK, let's 00:02:10.240 --> 00:02:12.340 unpack this wrecking ball concept then. We're 00:02:12.340 --> 00:02:14.560 going to explore this using a strict clinical 00:02:14.560 --> 00:02:16.740 reasoning pattern, right? Mechanism to physiologic 00:02:16.740 --> 00:02:18.919 effect, therapeutic use, adverse effects, and 00:02:18.919 --> 00:02:20.840 finally nursing interventions. That's the best 00:02:20.840 --> 00:02:23.479 way to do it. So if bacteria are building a wall 00:02:23.479 --> 00:02:25.960 to protect themselves, how exactly does vancomycin 00:02:25.960 --> 00:02:28.860 tear it down and why does it only destroy certain 00:02:28.860 --> 00:02:31.000 castles? Well, it's actually less of a wrecking 00:02:31.000 --> 00:02:33.439 ball and more of a saboteur, I'd say. A saboteur? 00:02:33.520 --> 00:02:35.949 Yes. So the specific Lego bricks the bacteria 00:02:35.949 --> 00:02:39.129 use are called peptide precursor units. And at 00:02:39.129 --> 00:02:41.490 the very end of these units, there is a highly 00:02:41.490 --> 00:02:44.469 specific shape. It's a chemical tail called the 00:02:44.469 --> 00:02:49.030 D -alanine terminus. The D -alanine terminus. 00:02:49.110 --> 00:02:52.310 Got it. Right. And that tail is absolutely essential 00:02:52.310 --> 00:02:54.090 for the bacteria to link the bricks together. 00:02:54.729 --> 00:02:56.930 So vancomycin, which is a bactericidal drug, 00:02:57.349 --> 00:03:00.110 meaning it actively kills the bacteria. By doing 00:03:00.110 --> 00:03:04.060 what? By finding that exact de -aligning tail, 00:03:04.539 --> 00:03:07.039 and just clapping completely over it. Oh, wow. 00:03:07.419 --> 00:03:10.110 So basically... caps the Lego brick so nothing 00:03:10.110 --> 00:03:12.689 else can attach to it. Yes. It binds to it with 00:03:12.689 --> 00:03:15.590 incredible affinity. And by capping that terminus, 00:03:15.849 --> 00:03:18.909 vancomycin physically blocks the bacterial enzymes 00:03:18.909 --> 00:03:21.050 from doing their job. Which enzymes are those? 00:03:21.469 --> 00:03:24.449 Specifically, it inhibits peptidoglycan polymerase 00:03:24.449 --> 00:03:27.509 and the transpeptidation reactions. So they literally 00:03:27.509 --> 00:03:29.569 can't cross -link the wall. The building process 00:03:29.569 --> 00:03:31.810 just violently halts. And without the wall, what 00:03:31.810 --> 00:03:33.930 happens to the bacteria? The physiologic effect 00:03:33.930 --> 00:03:37.090 is a massive alteration of cell wall permeability. 00:03:37.400 --> 00:03:40.580 the wall becomes weak, highly permeable, and 00:03:40.580 --> 00:03:42.840 eventually the internal pressure of the bacterial 00:03:42.840 --> 00:03:45.039 cell causes it to just rupture and die. That 00:03:45.039 --> 00:03:47.259 sounds incredibly effective. I mean, if it's 00:03:47.259 --> 00:03:49.360 that destructive, why isn't it just a universal 00:03:49.360 --> 00:03:51.400 cure -all? Why wouldn't we use it for every single 00:03:51.400 --> 00:03:54.840 infection? It really comes down to access. Vancomycin 00:03:54.840 --> 00:03:58.419 is a massive, bulky molecule. Gram -positive 00:03:58.419 --> 00:04:02.000 bacteria like MRSA, streptococcus and enterococcus, 00:04:02.199 --> 00:04:05.300 they have a very thick but exposed outer layer. 00:04:05.419 --> 00:04:08.319 So the targets are easy to reach. Exactly. Those 00:04:08.319 --> 00:04:11.099 D -alanine targets are right there for the taking. 00:04:11.659 --> 00:04:14.080 But gram -negative bacteria have an extra outer 00:04:14.080 --> 00:04:16.879 lipid membrane. It acts like a microscopic force 00:04:16.879 --> 00:04:20.240 field. Ah, I see. So vancomycin is simply too 00:04:20.240 --> 00:04:22.600 large to pass through that lipid shield to reach 00:04:22.600 --> 00:04:25.000 the targets underneath, meaning it is strictly 00:04:25.000 --> 00:04:28.060 a gram positive specialist. It has zero activity 00:04:28.060 --> 00:04:30.319 against gram negatives or fungi. So we're talking 00:04:30.319 --> 00:04:32.180 about a highly specialized weapon here. Let's 00:04:32.180 --> 00:04:34.459 look at when a medical team actually reaches 00:04:34.459 --> 00:04:37.379 for it. Imagine a patient in the ICU, right? 00:04:37.709 --> 00:04:39.870 their blood pressure is plummeting, they're in 00:04:39.870 --> 00:04:42.290 septic shock, and the team suspects a massive 00:04:42.290 --> 00:04:44.689 bloodstream infection. Yeah, a very common scenario. 00:04:44.750 --> 00:04:46.949 And they're dealing with methicillin -resistant 00:04:46.949 --> 00:04:50.670 Staphylococcus aureus, or MRSA, or maybe the 00:04:50.670 --> 00:04:53.170 patient has a severe, life -threatening beta 00:04:53.170 --> 00:04:55.750 -lactam allergy to penicillin. That is when the 00:04:55.750 --> 00:04:58.269 spread comes out, right? Absolutely. In those 00:04:58.269 --> 00:05:01.410 critical scenarios, vancomycin is the gold standard 00:05:01.410 --> 00:05:04.790 big gun. It's the preferred agent for serious 00:05:04.790 --> 00:05:07.589 resistant gram -positive systemic infections. 00:05:07.889 --> 00:05:10.629 Right. But what's fascinating here is that getting 00:05:10.629 --> 00:05:13.350 the dosing right is incredibly counterintuitive. 00:05:14.199 --> 00:05:16.839 Vancomycin exhibits a property called concentration 00:05:16.839 --> 00:05:19.100 -independent killing. Yeah, I was reading the 00:05:19.100 --> 00:05:21.399 source notes on that, and it frankly broke my 00:05:21.399 --> 00:05:23.540 brain a little bit. Oh, really? Because if a 00:05:23.540 --> 00:05:26.620 patient is dying of a severe infection, my instinct 00:05:26.620 --> 00:05:28.680 would just be to flood their system with the 00:05:28.680 --> 00:05:30.959 biggest dose possible, you know, to kill the 00:05:30.959 --> 00:05:33.120 bacteria faster. Why wouldn't that work? Because 00:05:33.120 --> 00:05:35.899 of the saturation point. Imagine a factory assembly 00:05:35.899 --> 00:05:38.740 line. If you put 10 workers on the line, production 00:05:38.740 --> 00:05:41.800 maxes out. Adding 100 more workers won't speed 00:05:41.800 --> 00:05:43.470 anything up. They'll just get in each other's 00:05:43.470 --> 00:05:45.370 way. Exactly. They'll just cause damage. Yeah. 00:05:45.670 --> 00:05:48.209 Once the drug concentration in the blood reaches 00:05:48.209 --> 00:05:50.910 a certain level, what we call the minimum inhibitory 00:05:50.910 --> 00:05:54.430 concentration, or MIC, the bacterial killing 00:05:54.430 --> 00:05:57.350 rate maxes out. So more drug doesn't equal more 00:05:57.350 --> 00:06:00.189 dead bugs. Right. Pushing the concentration higher 00:06:00.189 --> 00:06:03.509 doesn't kill more bugs at all. It just wildly 00:06:03.509 --> 00:06:06.009 increases the toxicity to the patient. Then how 00:06:06.009 --> 00:06:08.230 does a clinician track if they're actually giving 00:06:08.230 --> 00:06:10.420 the right amount? the sources kept drawing around 00:06:10.420 --> 00:06:14.579 this acronym, the AUC to MIC ratio. What does 00:06:14.579 --> 00:06:16.360 that actually mean for the patient in the bed? 00:06:16.500 --> 00:06:20.199 So the AUC stands for area under the curve. It's 00:06:20.199 --> 00:06:22.699 basically a way of calculating the total overall 00:06:22.699 --> 00:06:25.279 exposure to the drug that the bacteria experience 00:06:25.279 --> 00:06:28.379 over a full 24 -hour period. OK. And as we just 00:06:28.379 --> 00:06:31.019 mentioned, MIC is the minimum inhibitory concentration, 00:06:31.660 --> 00:06:33.759 the lowest amount needed to stop those specific 00:06:33.759 --> 00:06:36.639 bacteria from growing. The current clinical standard 00:06:36.639 --> 00:06:39.560 for effectiveness is to maintain an AUC to MIC 00:06:39.560 --> 00:06:42.480 ratio of 400 or more. Wait, meaning the total 00:06:42.480 --> 00:06:45.560 24 -hour drug exposure needs to be at least 400 00:06:45.560 --> 00:06:48.300 times that absolute minimum threshold. Correct. 00:06:48.560 --> 00:06:51.439 And the stakes for hitting that number are terrifyingly 00:06:51.439 --> 00:06:53.600 high. The data shows that if that ratio drops 00:06:53.600 --> 00:06:55.939 below 400, it doesn't just mean the drug isn't 00:06:55.939 --> 00:06:57.930 working well. What does it mean? It actually 00:06:57.930 --> 00:07:00.370 potentiates the emergence of resistance. You 00:07:00.370 --> 00:07:02.810 start creating vancomycin intermediate strains. 00:07:03.410 --> 00:07:06.149 You're essentially just vaccinating the bacteria, 00:07:06.370 --> 00:07:08.550 training them to survive our strongest weapon. 00:07:09.029 --> 00:07:11.470 Wow. So the medical team has to hit hard enough 00:07:11.470 --> 00:07:14.370 to completely wipe them out. but not so hard 00:07:14.370 --> 00:07:16.769 that they poison the patient. Exactly. That is 00:07:16.769 --> 00:07:19.610 a terrifying balancing act. And speaking of getting 00:07:19.610 --> 00:07:22.189 the drug into the system, the sources detail 00:07:22.189 --> 00:07:24.610 some really strict protocols on how this drug 00:07:24.610 --> 00:07:27.649 is delivered. Oh, yes. The route of administration 00:07:27.649 --> 00:07:30.189 is arguably one of the most critical concepts 00:07:30.189 --> 00:07:32.850 for anyone handling this drug to grasp. It is 00:07:32.850 --> 00:07:35.389 a massive safety and efficacy consideration. 00:07:35.449 --> 00:07:36.970 Wait, hold on. Let me push back on that a bit. 00:07:37.170 --> 00:07:40.149 If I have a patient with a systemic MRSA infection, 00:07:40.250 --> 00:07:42.170 maybe in their blood or deep in their bone like 00:07:42.170 --> 00:07:45.420 osteomyelitis, Why are we dealing with IV drips 00:07:45.420 --> 00:07:47.480 and complicated calculations at all? I saw in 00:07:47.480 --> 00:07:49.920 the data that they manufacture oral formulations 00:07:49.920 --> 00:07:52.720 of vancomycin, like pills and liquids. Why not 00:07:52.720 --> 00:07:54.319 just give them the pill and save them the IV 00:07:54.319 --> 00:07:56.879 line? It's because of a fascinating quirk in 00:07:56.879 --> 00:08:00.660 the drug's pharmacokinetics. The oral bioavailability 00:08:00.660 --> 00:08:04.540 of vancomycin is virtually zero. Zero? Like literally 00:08:04.540 --> 00:08:06.839 none of it gets absorbed into the blood? Almost 00:08:06.839 --> 00:08:09.740 none. It is essentially unabsorbed from a normal 00:08:09.740 --> 00:08:12.290 gastrointestinal tract. If you give a patient 00:08:12.290 --> 00:08:15.569 an oral dose of Ancomycin for a systemic bloodstream 00:08:15.569 --> 00:08:18.709 infection, the drug cannot cross the intestinal 00:08:18.709 --> 00:08:21.649 wall into the blood. So where does it go? It'll 00:08:21.649 --> 00:08:23.449 literally just pass right through the digestive 00:08:23.449 --> 00:08:26.350 system and end up in their stool. The urinary 00:08:26.350 --> 00:08:29.009 recovery of an oral dose doesn't even exceed 00:08:29.009 --> 00:08:32.690 0 .76%. That is wild! Yeah, you'd be giving them 00:08:32.690 --> 00:08:34.850 zero systemic treatment and the patient would 00:08:34.850 --> 00:08:36.909 likely succumb to the untreated blood infection. 00:08:37.389 --> 00:08:40.970 Okay, so... IV administration is absolutely mandatory 00:08:40.970 --> 00:08:44.250 for any systemic infection. Bacteremia, endocarditis, 00:08:44.409 --> 00:08:47.090 pneumonia, severe skin infections, all of those 00:08:47.090 --> 00:08:49.529 require IV vancomycin. Without question. But 00:08:49.529 --> 00:08:52.570 if the oral absorption is zero, why do pharmaceutical 00:08:52.570 --> 00:08:54.889 companies even bother making pills or liquids? 00:08:55.549 --> 00:08:57.629 What is the point of a drug that stays entirely 00:08:57.629 --> 00:09:00.750 trapped in the gut? Because sometimes the crisis 00:09:00.750 --> 00:09:03.909 is trapped inside the gut with it. Oral vancomycin, 00:09:04.169 --> 00:09:06.970 or enteral administration, is used exclusively 00:09:06.970 --> 00:09:09.769 for localized gastrointestinal infections. Oh, 00:09:09.990 --> 00:09:13.529 like C. diff. Exactly. It is a first -line therapy 00:09:13.529 --> 00:09:16.870 for clostridioids. difficilely associated diarrhea, 00:09:17.389 --> 00:09:20.889 or C. diff, and enterocolitis caused by Staphylococcus 00:09:20.889 --> 00:09:23.370 aureus. That makes total sense. It's essentially 00:09:23.370 --> 00:09:26.210 a targeted gut bomb. You swallow it. It stays 00:09:26.210 --> 00:09:28.889 completely in the intestines. And it just concentrates 00:09:28.889 --> 00:09:31.669 its wrecking ball power right where the C. diff 00:09:31.669 --> 00:09:34.190 bacteria are wreaking havoc. And all without 00:09:34.190 --> 00:09:36.350 exposing the rest of the body to the heavy duty 00:09:36.350 --> 00:09:39.549 drug. Right. So what's the typical dose for that? 00:09:39.909 --> 00:09:42.269 For an adult's initial episode of C. diff, it's 00:09:42.269 --> 00:09:45.309 typically around 125 milligrams taken four times 00:09:45.309 --> 00:09:47.610 a day for 10 days. And I saw there are liquid 00:09:47.610 --> 00:09:50.250 versions too. Yeah. The sources note that oral 00:09:50.250 --> 00:09:53.169 liquid formulations can be prepared using a compounding 00:09:53.169 --> 00:09:56.309 kit with a grape flavored diluent, which is huge 00:09:56.309 --> 00:09:58.649 for pediatric patients. Oh, that's a great clinical 00:09:58.649 --> 00:10:01.370 pearl. But the golden rule never changes. The 00:10:01.370 --> 00:10:03.870 oral route is strictly for the gut and the IV 00:10:03.870 --> 00:10:07.049 route is strictly for systemic infections. Mixing 00:10:07.049 --> 00:10:09.250 up those indications is a catastrophic clinical 00:10:09.250 --> 00:10:12.740 error. So what does this all mean for the nurse 00:10:12.740 --> 00:10:15.679 at the bedside hooking up the IV bag? Because 00:10:15.679 --> 00:10:18.419 getting the drug directly into the blood introduces 00:10:18.419 --> 00:10:21.379 a whole new set of massive challenges, right? 00:10:21.440 --> 00:10:23.740 It absolutely does. The preparation of the IV 00:10:23.740 --> 00:10:26.159 formulation sounds incredibly tedious. You can't 00:10:26.159 --> 00:10:28.299 just inject it straight in. No, the administration 00:10:28.299 --> 00:10:30.360 guidelines are very strict. You reconstitute 00:10:30.360 --> 00:10:33.779 the powder, but then further dilution is absolutely 00:10:33.779 --> 00:10:37.059 required. How much dilution? The standard protocol 00:10:37.059 --> 00:10:40.399 is to dilute it with a compatible IV fluid like 00:10:40.399 --> 00:10:44.639 normal saline or 5 % dextrose to a final concentration 00:10:44.639 --> 00:10:47.480 of five milligrams per milliliter. Wait, if a 00:10:47.480 --> 00:10:49.779 patient is getting a standard 1 ,000 milligram 00:10:49.779 --> 00:10:52.279 dose, that means you're pumping 200 milliliters 00:10:52.279 --> 00:10:55.039 of extra fluid into their veins. Yes. For a healthy 00:10:55.039 --> 00:10:57.480 person, fine. But what if you have a critically 00:10:57.480 --> 00:11:01.559 ill ICU patient in severe heart failure, or they 00:11:01.559 --> 00:11:04.000 have an acute kidney injury and they are severely 00:11:04.000 --> 00:11:06.240 fluid restricted. Every drop is pushing them 00:11:06.240 --> 00:11:08.620 closer to pulmonary edema. Can't they just concentrate 00:11:08.620 --> 00:11:11.539 it? Well, the sources do allow for a more concentrated 00:11:11.539 --> 00:11:13.879 solution, up to 10 milligrams per milliliter, 00:11:14.279 --> 00:11:16.120 for patients in desperate need of fluid restriction. 00:11:16.220 --> 00:11:18.899 Okay, good. However, you trust a whole new crisis 00:11:18.899 --> 00:11:22.019 when you do that. Pushing highly concentrated 00:11:22.019 --> 00:11:25.600 vancomycin or pushing it too fast directly causes 00:11:25.600 --> 00:11:28.620 its most famous adverse effect. The infusion 00:11:28.620 --> 00:11:31.159 reaction. Exactly. Historically the medical community 00:11:31.159 --> 00:11:33.879 called this red man syndrome, though the updated 00:11:33.879 --> 00:11:37.000 clinical terminology is simply vancomycin infusion 00:11:37.000 --> 00:11:39.179 reaction. Right, I've heard of that. It's classified 00:11:39.179 --> 00:11:41.799 as a rapid to moderate adverse reaction, and 00:11:41.799 --> 00:11:44.500 it is entirely rate dependent. You know, I always 00:11:44.500 --> 00:11:46.379 assumed that was an allergic reaction, like when 00:11:46.379 --> 00:11:48.120 someone is allergic to peanuts and their throat 00:11:48.120 --> 00:11:50.059 closes up. It's a very common misconception. 00:11:50.820 --> 00:11:54.220 But it is not a true IgE -mediated anaphylactic 00:11:54.220 --> 00:11:57.259 allergy. The patient's immune system isn't actually 00:11:57.259 --> 00:11:59.659 targeting the vancomycin molecule itself. Then 00:11:59.659 --> 00:12:02.700 what causes it? The reaction happens purely because 00:12:02.700 --> 00:12:05.240 of the sheer physical insult of pushing this 00:12:05.240 --> 00:12:08.200 massive molecule into the vein too quickly. The 00:12:08.200 --> 00:12:11.179 rapid influx triggers a sudden violent degranulation 00:12:11.179 --> 00:12:13.860 of mass cells and basophils. Basically the immune 00:12:13.860 --> 00:12:16.500 cells just panic and burst open. Yes. And when 00:12:16.500 --> 00:12:19.220 they burst, they dump massive amounts of histamine 00:12:19.220 --> 00:12:21.700 directly into the bloodstream. Oh, and histamine 00:12:21.700 --> 00:12:24.320 is the primary chemical that causes all classic 00:12:24.320 --> 00:12:27.039 allergy symptoms. So even though it's not a true 00:12:27.039 --> 00:12:29.440 allergy, the symptoms look identical. Exactly. 00:12:29.820 --> 00:12:32.460 The patient suddenly experiences severe flushing. 00:12:32.679 --> 00:12:35.740 usually radiating up the upper torso, their neck, 00:12:35.799 --> 00:12:39.220 and face, they get intense erythema and pruritus 00:12:39.220 --> 00:12:41.980 severe itching. And it gets worse. Right. Because 00:12:41.980 --> 00:12:44.360 histamine causes blood vessels to rapidly dilate 00:12:44.360 --> 00:12:46.460 and smooth muscle in the lungs to constrict, 00:12:46.820 --> 00:12:48.879 they can develop wheezing, shortness of breath, 00:12:48.960 --> 00:12:51.820 and a sudden, highly dangerous drop in blood 00:12:51.820 --> 00:12:55.419 pressure. Hypotension. This is exactly why the 00:12:55.419 --> 00:12:57.580 priority nursing intervention is directly tied 00:12:57.580 --> 00:13:00.830 to the clock. you must infuse vancomycin slowly. 00:13:00.870 --> 00:13:03.870 How slowly? The absolute minimum infusion time 00:13:03.870 --> 00:13:06.570 is over at least one hour or at a recommended 00:13:06.570 --> 00:13:09.049 rate of 10 to 15 milligrams per minute. Wow, 00:13:09.090 --> 00:13:11.309 at least an hour. Yeah, and if you are giving 00:13:11.309 --> 00:13:13.889 a massive loading dose, you might need to extend 00:13:13.889 --> 00:13:16.450 that drip over two or even three hours to prevent 00:13:16.450 --> 00:13:19.129 the mast cells from panicking. Okay, say a clinician 00:13:19.129 --> 00:13:21.850 is at the bedside, the drip is running, and suddenly 00:13:21.850 --> 00:13:24.649 the patient turns bright red, their pressure 00:13:24.649 --> 00:13:27.129 tanks, and they start tearing at their skin. 00:13:27.769 --> 00:13:30.769 What is the immediate intervention? I feel like 00:13:30.769 --> 00:13:33.889 the instinct would be to grab epinephrine. Because 00:13:33.889 --> 00:13:36.970 it's not true anaphylaxis, epinephrine usually 00:13:36.970 --> 00:13:40.029 isn't the first move. The immediate critical 00:13:40.029 --> 00:13:42.830 intervention is to stop or significantly slow 00:13:42.830 --> 00:13:46.470 the infusion. Just stop the IV. Right. Usually 00:13:46.470 --> 00:13:48.409 if you just stop the drug from entering the blood 00:13:48.409 --> 00:13:50.610 and give the body a few minutes to clear the 00:13:50.610 --> 00:13:53.210 circulating histamine, the symptoms will subside. 00:13:53.490 --> 00:13:56.110 Do they give anything else? The team might administer 00:13:56.110 --> 00:13:58.450 an antihistamine, like diphenhydramine, to help 00:13:58.450 --> 00:14:01.370 calm the receptors. Once the patient stabilizes, 00:14:01.409 --> 00:14:03.610 you can usually restart the infusion at a much 00:14:03.610 --> 00:14:06.850 slower tolerated rate. OK, that handles the immediate 00:14:06.850 --> 00:14:09.549 danger of getting the drug into the body. But 00:14:09.549 --> 00:14:11.549 once it's circulating, it still has to be filtered 00:14:11.549 --> 00:14:14.409 out. And that brings us to the delayed severe 00:14:14.409 --> 00:14:16.909 complications that develop over days of therapy. 00:14:16.929 --> 00:14:19.769 Right, the toxicities. Because vancomycin isn't 00:14:19.769 --> 00:14:21.950 processed by the liver, it's cleared almost entirely 00:14:21.950 --> 00:14:25.009 by the kidneys. And that clearance process is 00:14:25.009 --> 00:14:28.450 brutal. The two major heavy hitters that every 00:14:28.450 --> 00:14:31.549 clinician needs to monitor for constantly are 00:14:31.549 --> 00:14:35.210 nephrotoxicity and ototoxicity. I try to picture 00:14:35.210 --> 00:14:37.669 the kidneys filtration system like an incredibly 00:14:37.669 --> 00:14:40.690 fine delicate sieve. And vancomycin molecules 00:14:40.690 --> 00:14:43.549 are like massive jagged boulders just tumbling 00:14:43.549 --> 00:14:45.389 through the blood. That's a great analogy. If 00:14:45.389 --> 00:14:47.250 you force too many of those boulders through 00:14:47.250 --> 00:14:49.429 that delicate sieve for too long, you're going 00:14:49.429 --> 00:14:52.399 to rip the sieve apart. That's nephrotoxicity. 00:14:53.000 --> 00:14:55.340 Damage to the kidneys, which presents as renal 00:14:55.340 --> 00:14:58.539 failure or azotemia, a dangerous buildup of nitrogenous 00:14:58.539 --> 00:15:00.600 waste in the blood. That's a very accurate way 00:15:00.600 --> 00:15:03.000 to visualize the physical toll it takes. And 00:15:03.000 --> 00:15:05.450 odor toxicity is damage to the inner ear. or 00:15:05.450 --> 00:15:07.570 the eighth cranial nerve. Which causes what? 00:15:07.809 --> 00:15:10.370 That can present as permanent hearing loss, ringing 00:15:10.370 --> 00:15:13.149 in the ears tinnitus or severe vertigo. These 00:15:13.149 --> 00:15:15.649 delayed toxicities are precisely why we don't 00:15:15.649 --> 00:15:19.250 just guess the dose and why that AUC to MIC ratio 00:15:19.250 --> 00:15:21.710 we talked about earlier is so vital. Exactly. 00:15:21.879 --> 00:15:23.840 The medical team is constantly drawing blood, 00:15:24.340 --> 00:15:26.360 checking trough levels, making sure the concentration 00:15:26.360 --> 00:15:29.240 is high enough to kill the MRSA, but low enough 00:15:29.240 --> 00:15:32.399 to protect those delicate kidney sieves and auditory 00:15:32.399 --> 00:15:34.960 nerves. But this high wire act gets even more 00:15:34.960 --> 00:15:37.039 complicated when we look at drug interactions 00:15:37.039 --> 00:15:39.200 in the critical care setting, right? Well, it 00:15:39.200 --> 00:15:41.659 really does. We established that the infusion 00:15:41.659 --> 00:15:44.940 reaction is driven by a massive histamine dump. 00:15:45.080 --> 00:15:48.159 Because of that, the medical team has to be incredibly 00:15:48.159 --> 00:15:50.860 vigilant about what other medications they're 00:15:50.860 --> 00:15:53.240 giving at the exact same time. The sources highlight 00:15:53.240 --> 00:15:55.919 a really fascinating kind of desperate scenario 00:15:55.919 --> 00:15:59.580 here. Vancomycin desensitization protocols. Yes. 00:16:00.029 --> 00:16:02.090 Very tricky. What happens when you have a patient 00:16:02.090 --> 00:16:05.190 who has a documented true life -threatening allergy 00:16:05.190 --> 00:16:08.110 to vancomycin, but they have an MRSA infection 00:16:08.110 --> 00:16:10.250 that is going to kill them and vancomycin is 00:16:10.250 --> 00:16:13.070 the absolute last resort? It's the ultimate rock 00:16:13.070 --> 00:16:14.850 -and -a -heart -place scenario. In those rare 00:16:14.850 --> 00:16:18.429 cases, clinicians will use a rapid or slow desensitization 00:16:18.429 --> 00:16:20.730 protocol. How does that work? They introduce 00:16:20.730 --> 00:16:24.610 microscopic, slowly increasing doses of vancomycin 00:16:24.610 --> 00:16:27.710 into the patient's system to try and temporarily 00:16:27.710 --> 00:16:30.279 exhaust the immune system's reactivity. They're 00:16:30.279 --> 00:16:32.419 building a very fragile tolerance. But the source 00:16:32.419 --> 00:16:35.059 material provides a massive warning here. If 00:16:35.059 --> 00:16:38.019 you are attempting that fragile desensitization, 00:16:38.700 --> 00:16:41.220 any concomitant use of other medications that 00:16:41.220 --> 00:16:44.000 also induce histamine can cause the entire protocol 00:16:44.000 --> 00:16:46.440 to fail catastrophically. And those histamine 00:16:46.440 --> 00:16:49.500 -inducing drugs are absolute staples of ICU care. 00:16:49.820 --> 00:16:52.259 Like what? We are talking about propofol. which 00:16:52.259 --> 00:16:55.200 is used constantly for sedation. Opioids like 00:16:55.200 --> 00:16:58.019 morphine or fentanyl for pain. Muscle relaxants 00:16:58.019 --> 00:17:00.740 used for intubation. Even the radio contrast 00:17:00.740 --> 00:17:03.980 dyes used for CT scans. Wow, all of those. Yes. 00:17:04.299 --> 00:17:06.680 If you administer those while trying to desensitize 00:17:06.680 --> 00:17:09.099 a patient to vancomycin, you can trigger the 00:17:09.099 --> 00:17:10.900 exact histamine release you were trying to prevent. 00:17:11.059 --> 00:17:13.700 So they have to be... Withheld or changed exactly 00:17:13.700 --> 00:17:16.259 it requires a profound level of situational awareness 00:17:16.259 --> 00:17:18.000 from the clinical pharmacist and the bedside 00:17:18.000 --> 00:17:20.599 nurse You're just managing one antibiotic. You're 00:17:20.599 --> 00:17:23.279 managing the entire pharmacological ecosystem 00:17:23.279 --> 00:17:26.039 of that patient Incredible. Okay. Here's where 00:17:26.039 --> 00:17:28.980 it gets really interesting if we aggressively 00:17:28.980 --> 00:17:31.940 distill all of this down to the absolute essentials 00:17:31.940 --> 00:17:35.259 The highest yield clinical realities that determine 00:17:35.259 --> 00:17:37.960 whether a patient survives this therapy. What 00:17:37.960 --> 00:17:39.920 does that look like? Let's do the 80 -20 review. 00:17:39.960 --> 00:17:42.640 Let's do it The first essential reality is the 00:17:42.640 --> 00:17:45.259 evaluation of effectiveness. We mentioned the 00:17:45.259 --> 00:17:48.539 kidneys are the delicate sieves. Because vancomycin 00:17:48.539 --> 00:17:51.900 is cleared almost entirely by those sieves, therapeutic 00:17:51.900 --> 00:17:55.740 drug monitoring, or TDM, is essential. The patient's 00:17:55.740 --> 00:17:58.220 baseline renal function, specifically their serum 00:17:58.220 --> 00:18:01.240 creatinine and creatinine clearance, must dictate 00:18:01.240 --> 00:18:03.890 the dosing interval. Meaning, if a patient has 00:18:03.890 --> 00:18:06.329 healthy kidneys, they might get a fresh bag of 00:18:06.329 --> 00:18:09.849 IV vancomycin every 8 to 12 hours. But if those 00:18:09.849 --> 00:18:11.710 sieves are already damaged, if the creatinine 00:18:11.710 --> 00:18:14.009 clearance plummets, the drug can't escape the 00:18:14.009 --> 00:18:16.069 body. That interval has to be extended drastically. 00:18:16.210 --> 00:18:18.970 They might only get a dose every 24 or even 48 00:18:18.970 --> 00:18:21.809 hours. Exactly. If the team fail to adjust for 00:18:21.809 --> 00:18:23.930 renal function, the drug will just accumulate 00:18:23.930 --> 00:18:25.670 and destroy whatever kidney function they have 00:18:25.670 --> 00:18:28.099 left. It is the ultimate priority check. OK, 00:18:28.180 --> 00:18:29.819 I have a quick memory hook for everyone before 00:18:29.819 --> 00:18:31.779 we hit the top five facts. Oh, let's hear it. 00:18:31.900 --> 00:18:35.319 Think of vancomycin driving a huge van to block 00:18:35.319 --> 00:18:38.799 the bacterial D -alanine crosswalk. But watch 00:18:38.799 --> 00:18:41.140 out. The van has incredibly loud sirens. That's 00:18:41.140 --> 00:18:44.799 the ototoxicity. And it leaks motor oil everywhere. 00:18:45.039 --> 00:18:47.990 That's the nephrotoxicity. Ah. I love that. The 00:18:47.990 --> 00:18:50.490 van blocking the crosswalks, loud sirens, leaking 00:18:50.490 --> 00:18:53.230 oil. That's perfect for an exam. All right. Pulling 00:18:53.230 --> 00:18:55.269 all the threads together. If you remember nothing 00:18:55.269 --> 00:18:57.509 else, here are the top five clinical facts from 00:18:57.509 --> 00:18:59.450 the sources. I'll take the first one. Go for 00:18:59.450 --> 00:19:02.369 it. Number one, mechanistically, vancomycin is 00:19:02.369 --> 00:19:05.150 a glycopeptide antibiotic that binds specifically 00:19:05.150 --> 00:19:09.210 to the D -alanine terminus. It is exclusively 00:19:09.210 --> 00:19:12.549 a wrecker of gram positive fortresses like MRSA 00:19:12.549 --> 00:19:15.470 and Enterococcus. Perfect. Number two, the key 00:19:15.470 --> 00:19:18.359 medication difference. The route dictates the 00:19:18.359 --> 00:19:21.299 reality. The oral formulation has zero systemic 00:19:21.299 --> 00:19:24.160 absorption. None. A vancomycin pill is useless 00:19:24.160 --> 00:19:26.859 for a blood infection. It is a targeted gut bomb 00:19:26.859 --> 00:19:29.299 used strictly for localized intestinal infections 00:19:29.299 --> 00:19:33.089 like C. diff. 3. If you are using it systemically 00:19:33.089 --> 00:19:36.549 via IV, rapid administration will trigger a massive 00:19:36.549 --> 00:19:38.849 histamine release infusion reaction, causing 00:19:38.849 --> 00:19:40.829 the patient to flush red and their blood pressure 00:19:40.829 --> 00:19:43.609 to crash. The priority nursing intervention is 00:19:43.609 --> 00:19:46.829 non -negotiable. Infuse it slowly over at least 00:19:46.829 --> 00:19:51.779 an hour. 4. Major safety concerns. It is highly 00:19:51.779 --> 00:19:54.200 nephrotoxic to the kidneys and odor toxic to 00:19:54.200 --> 00:19:56.779 the ears. You cannot fly blind here. Right. It 00:19:56.779 --> 00:19:59.119 requires continuous therapeutic drug monitoring, 00:19:59.500 --> 00:20:03.380 aiming for that AUC to MIC ratio of 400 or greater 00:20:03.380 --> 00:20:05.440 to kill the bugs without breeding resistance. 00:20:05.660 --> 00:20:07.880 And finally, number five, because it is cleared 00:20:07.880 --> 00:20:10.359 by the kidneys, the dosage frequency is heavily 00:20:10.359 --> 00:20:13.000 inherently dependent on renal function and creatinine 00:20:13.000 --> 00:20:15.160 clearance. That is the 20 % you absolutely need 00:20:15.160 --> 00:20:17.319 to know. That really is the high wire act of 00:20:17.319 --> 00:20:19.680 critical care pharmacology. now have the elite 00:20:19.680 --> 00:20:22.259 clinical perspective on vancomycin. You understand 00:20:22.259 --> 00:20:24.599 how the wrecking ball works, why it can be so 00:20:24.599 --> 00:20:26.740 dangerous to the patient, and the incredibly 00:20:26.740 --> 00:20:29.240 precise interventions required to manage it safely. 00:20:29.480 --> 00:20:48.359 Thank you for joining us on this deep dive. de 00:20:48.359 --> 00:20:50.819 -alanine tail of the bacterial cell wall. Right. 00:20:50.900 --> 00:20:53.339 It clamps on, the wall crumbles, the bacteria 00:20:53.339 --> 00:20:57.200 die. But bacteria are ancient, relentless survival 00:20:57.200 --> 00:21:00.859 machines. They mutate. And the sources detail 00:21:00.859 --> 00:21:04.460 exactly how certain strains, specifically vancomycin 00:21:04.460 --> 00:21:07.579 -resistant enderococci or VRE, have managed to 00:21:07.579 --> 00:21:09.900 beat our biggest gun. How do they do it? Through 00:21:09.900 --> 00:21:12.700 exchanging microscopic plasmids of DNA, these 00:21:12.700 --> 00:21:15.039 bacteria actually rewrite their own genetic code 00:21:15.039 --> 00:21:17.500 for building their cell wall. Instead of building 00:21:17.500 --> 00:21:21.099 that D -alanine tail, they swap out the very 00:21:21.099 --> 00:21:23.259 last molecule. They build a D -alanine -D -lactate 00:21:23.259 --> 00:21:25.480 tail instead. Wait, they just swap out a single 00:21:25.480 --> 00:21:27.980 structural molecule? One single molecule. And 00:21:27.980 --> 00:21:30.359 that one microscopic change alters the shape 00:21:30.359 --> 00:21:32.819 of the tail just enough that vancomycin's binding 00:21:32.819 --> 00:21:35.539 affinity drops to almost zero. Oh, wow. The wrecking 00:21:35.539 --> 00:21:37.980 ball just bounces off. The lock has been changed. 00:21:38.160 --> 00:21:40.819 As a clinician or a scientist, this is the humbling 00:21:40.819 --> 00:21:43.319 reality you face. Every time we deploy our most 00:21:43.319 --> 00:21:46.099 powerful antibiotics, we have to ask ourselves, 00:21:46.259 --> 00:21:48.160 how are the bacteria mutating right under our 00:21:48.160 --> 00:21:51.519 noses to survive? The arms race never truly ends. 00:21:51.740 --> 00:21:54.319 And that means the learning never ends. Stay 00:21:54.319 --> 00:21:56.680 curious, stay vigilant, and we will see you on 00:21:56.680 --> 00:21:57.759 the next Deep Dive.