WEBVTT 00:00:00.000 --> 00:00:02.540 Welcome to the Deep Dive. Today we're tackling 00:00:02.540 --> 00:00:06.000 clindamycin. It's a really fascinating antibiotic, 00:00:06.179 --> 00:00:08.140 one that's actually been a staple for quite some 00:00:08.140 --> 00:00:10.640 time, but still plays a, well, a pretty vital 00:00:10.640 --> 00:00:12.740 role in medicine today. It really does. You can 00:00:12.740 --> 00:00:17.640 think of it like a disruptor for bacteria. It 00:00:17.640 --> 00:00:19.820 essentially stops them from building the proteins 00:00:19.820 --> 00:00:23.199 they absolutely need to survive and multiply. 00:00:23.420 --> 00:00:26.260 And it came about by modifying another antibiotic, 00:00:26.460 --> 00:00:29.199 right? Lincomycin. Exactly. A chemical tweak, 00:00:29.460 --> 00:00:33.460 specifically adding a chlorine atom, turned lincomycin 00:00:33.460 --> 00:00:37.140 into clindamycin. And it's relatively small, 00:00:37.280 --> 00:00:40.170 molecule -wise. but packs a punch against a lot 00:00:40.170 --> 00:00:41.929 of different bacteria. It does. And you see it 00:00:41.929 --> 00:00:43.350 in different forms, too, don't you? Like, not 00:00:43.350 --> 00:00:45.189 just pills. Oh, yeah, absolutely. You've got 00:00:45.189 --> 00:00:47.409 the IV solutions, often mixed with saline for 00:00:47.409 --> 00:00:49.710 more serious systemic infections. Then there 00:00:49.710 --> 00:00:51.469 are the oral capsules, probably the most common 00:00:51.469 --> 00:00:53.429 form people think of. And topicals, too, right? 00:00:53.750 --> 00:00:55.770 Creams and gels. Yep, topical solutions, gels, 00:00:56.090 --> 00:00:58.789 creams used directly on the skin, often for things 00:00:58.789 --> 00:01:01.049 like acne. So it's pretty versatile in how it 00:01:01.049 --> 00:01:03.409 gets delivered. It really is. And that versatility 00:01:03.409 --> 00:01:05.629 and its long history are exactly what we want 00:01:05.629 --> 00:01:08.349 to. dig into today. We've gathered quite a bit 00:01:08.349 --> 00:01:10.469 of info, how it got approved, how it actually 00:01:10.469 --> 00:01:12.849 works in the body, how it's manufactured, even 00:01:12.849 --> 00:01:15.450 some of the, let's say, regulatory hurdles and 00:01:15.450 --> 00:01:18.629 discussions around it. The goal is really to 00:01:18.629 --> 00:01:21.709 give you, our listener, a solid, rounded picture 00:01:21.709 --> 00:01:25.329 of clindamycin. Its history, its uses, the science 00:01:25.329 --> 00:01:27.430 behind it, and maybe some surprising facts along 00:01:27.430 --> 00:01:30.950 the way. Exactly. So let's get started. Where 00:01:30.950 --> 00:01:33.269 should we begin? Maybe the history, the approvals? 00:01:33.450 --> 00:01:35.400 Sounds good. Looking at the regulatory journey 00:01:35.400 --> 00:01:37.640 is always interesting. Clinomysin isn't new, 00:01:37.739 --> 00:01:40.959 as we said. The initial FDA approvals, the NDAs, 00:01:40.959 --> 00:01:43.659 or new drug applications, they go back quite 00:01:43.659 --> 00:01:46.400 a way. To the 70s, wasn't it? That's right. 1972, 00:01:46.599 --> 00:01:48.459 initially. And then another significant approval 00:01:48.459 --> 00:01:52.040 in 1989. But then more recently, in 2016, there 00:01:52.040 --> 00:01:56.000 was another submission, NDA 280A3. OK, so what 00:01:56.000 --> 00:01:58.260 was different about that one? Well, it was filed 00:01:58.260 --> 00:02:01.819 as what's called an original 505b2 application, 00:02:02.340 --> 00:02:05.700 which Sounds technical, but think of it as a 00:02:05.700 --> 00:02:08.199 pathway where the applicant can rely partly on 00:02:08.199 --> 00:02:11.000 existing studies or findings the FDA already 00:02:11.000 --> 00:02:14.060 has on file, maybe for the original lincomycin 00:02:14.060 --> 00:02:16.740 or earlier clindamycin approvals, rather than 00:02:16.740 --> 00:02:18.900 doing all the studies from scratch. Ah, okay, 00:02:19.039 --> 00:02:21.789 so building on previous knowledge. in a way, 00:02:22.069 --> 00:02:24.169 makes sense for a drug that's been around. Exactly. 00:02:24.270 --> 00:02:26.990 But it still requires demonstrating safety and 00:02:26.990 --> 00:02:28.909 effectiveness for the specific product being 00:02:28.909 --> 00:02:32.289 proposed. And that 2016 application, well, it 00:02:32.289 --> 00:02:33.810 wasn't quite the end of the story even then. 00:02:33.930 --> 00:02:36.810 Oh, what happened next? Later that same year, 00:02:37.090 --> 00:02:39.729 October 2016, there was an amendment submitted. 00:02:40.009 --> 00:02:41.849 This specifically addressed something called 00:02:41.849 --> 00:02:45.750 PLLR labeling. PLLR, what's that stand for? Physician 00:02:45.750 --> 00:02:48.000 labeling rule. It's all about standardizing the 00:02:48.000 --> 00:02:50.000 format and content of the prescribing information 00:02:50.000 --> 00:02:52.419 that doctors receive, making sure it's clear, 00:02:52.740 --> 00:02:54.400 organized, and highlights the key information 00:02:54.400 --> 00:02:56.939 effectively. So constantly refining how the information 00:02:56.939 --> 00:02:59.340 is presented to make it safer and easier to use. 00:02:59.659 --> 00:03:02.180 Precisely. Yeah. And the FDA really does focus 00:03:02.180 --> 00:03:04.979 on the details there. For that 2016 application, 00:03:04.979 --> 00:03:07.219 for example, there were discussions about the 00:03:07.219 --> 00:03:09.319 actual container and carton labeling. Like the 00:03:09.319 --> 00:03:11.280 box it comes in. Yeah, the box, the bottle label. 00:03:11.439 --> 00:03:14.240 The FDA and the applicant, a company called Solarity, 00:03:14.580 --> 00:03:17.219 agreed on specific changes to improve readability 00:03:17.219 --> 00:03:20.159 and, importantly, reduce the risk of medication 00:03:20.159 --> 00:03:23.080 errors. What kind of changes? Things that might 00:03:23.080 --> 00:03:26.419 seem small but are based on human factors research, 00:03:26.979 --> 00:03:28.860 like using clear black text on a plain white 00:03:28.860 --> 00:03:31.479 background and putting a distinct black outline 00:03:31.479 --> 00:03:33.520 just around the part that states the drug's strength. 00:03:33.780 --> 00:03:35.780 Little visual cues to make sure the right dose 00:03:35.780 --> 00:03:38.439 is grabbed off the shelf. Makes sense. It does. 00:03:38.750 --> 00:03:41.469 Preventable medication errors are a huge focus. 00:03:42.069 --> 00:03:44.610 And it wasn't just the outside packaging. The 00:03:44.610 --> 00:03:46.669 detailed leaflet inside, the full prescribing 00:03:46.669 --> 00:03:49.370 information also got scrutiny. Right. You mentioned 00:03:49.370 --> 00:03:51.830 the PLLR rules. What else was important there? 00:03:52.069 --> 00:03:54.490 Well, the FDA emphasized strict adherence to 00:03:54.490 --> 00:03:59.030 the regulations, specifically 21 CFR 201 .56. 00:03:59.430 --> 00:04:01.629 This dictates the structure. For instance, the 00:04:01.629 --> 00:04:04.250 main heading must be full prescribing information, 00:04:04.509 --> 00:04:08.009 bolded, all caps right at the top. OK. Standard 00:04:08.009 --> 00:04:11.400 format. And crucially, if the drug carries significant 00:04:11.400 --> 00:04:14.719 risks, the very first section must be a boxed 00:04:14.719 --> 00:04:18.180 warning, also bolded. This is for the most serious 00:04:18.180 --> 00:04:20.279 potential side effects, so it needs to be impossible 00:04:20.279 --> 00:04:22.939 to miss. Front and center. So formatting isn't 00:04:22.939 --> 00:04:25.500 just about looks, it's about safety communication. 00:04:25.759 --> 00:04:28.160 Absolutely critical. Now, stepping back from 00:04:28.160 --> 00:04:31.839 the labeling to the drug substance itself, clindamycin 00:04:31.839 --> 00:04:35.199 phosphate, how do we ensure the quality of that 00:04:35.199 --> 00:04:37.339 starting material? Good question. Is there a 00:04:37.339 --> 00:04:40.480 standard for that? Yes, there often is. In Europe, 00:04:40.480 --> 00:04:42.420 for instance, they use something called a CEP, 00:04:43.040 --> 00:04:44.980 a certificate of suitability to the European 00:04:44.980 --> 00:04:48.060 pharmacopoeia monographs. Okay, a CEP. Right. 00:04:48.360 --> 00:04:50.740 And we know from regulatory documents that the 00:04:50.740 --> 00:04:52.839 clindamycin phosphate used in some products has 00:04:52.839 --> 00:04:55.600 a CEP, and based on that, it has a retest period 00:04:55.600 --> 00:04:57.720 of three years when stored under the specific 00:04:57.720 --> 00:05:00.139 conditions. So that certificate is basically 00:05:00.139 --> 00:05:02.259 a quality guarantee for the active ingredient 00:05:02.259 --> 00:05:04.620 itself, showing it meets recognized standards. 00:05:04.779 --> 00:05:07.300 Essentially, yes. It streamlines the regulatory 00:05:07.300 --> 00:05:09.199 process by confirming the quality of the raw 00:05:09.199 --> 00:05:12.319 material up front. Got it. Okay, so we've covered 00:05:12.319 --> 00:05:15.019 the approvals, the labeling focus, the quality 00:05:15.019 --> 00:05:17.879 control. Now, let's shift to what clindamycin 00:05:17.879 --> 00:05:20.560 actually does clinically. What's it used for? 00:05:20.860 --> 00:05:23.560 It's used for quite a broad spectrum of bacterial 00:05:23.560 --> 00:05:26.139 infections. One really common and important use 00:05:26.139 --> 00:05:28.899 is surgical prophylaxis. Preventing infections 00:05:28.899 --> 00:05:32.500 before they start during surgery. Exactly. Especially 00:05:32.500 --> 00:05:34.819 in patients who have allergies to beta -lactam 00:05:34.819 --> 00:05:38.160 antibiotics, like penicillin or cefasolin, which 00:05:38.160 --> 00:05:41.319 are often the first choice for prophylaxis. Clenomycin 00:05:41.319 --> 00:05:44.519 is a key alternative there. Ah, okay. So if you're 00:05:44.519 --> 00:05:46.699 allergic to penicillin and need surgery, you 00:05:46.699 --> 00:05:49.300 might get clenomycin beforehand. What else? It's 00:05:49.300 --> 00:05:52.079 also used in pregnancy. both for preventing and 00:05:52.079 --> 00:05:54.360 treating certain infections. And it's important 00:05:54.360 --> 00:05:56.399 in managing diabetic foot infections. Those can 00:05:56.399 --> 00:05:58.360 be really nasty and hard to treat, right? They 00:05:58.360 --> 00:06:00.720 can. And clindamycin is also frequently used 00:06:00.720 --> 00:06:03.180 for bone and joint infections. That includes 00:06:03.180 --> 00:06:05.959 infections related to fractures or even infections 00:06:05.959 --> 00:06:08.819 around artificial joints like hip or knee replacements. 00:06:09.000 --> 00:06:11.220 Does it get into bone well? That seems important 00:06:11.220 --> 00:06:14.180 for those kinds of infections. It does. And that's 00:06:14.180 --> 00:06:16.480 a key reason for its use there. We can talk more 00:06:16.480 --> 00:06:19.040 about its distribution later, but yes, its ability 00:06:19.040 --> 00:06:22.040 to penetrate bone tissue is a significant advantage. 00:06:22.560 --> 00:06:25.240 OK, good to know. What about specific bacteria? 00:06:25.399 --> 00:06:29.040 Is it ever a first line choice? Sometimes, yes. 00:06:29.519 --> 00:06:32.240 For instance, in pregnant women allergic to penicillin 00:06:32.240 --> 00:06:36.500 who have group B strep, streptococcus agalaxiae, 00:06:36.639 --> 00:06:39.240 clindamycin can be a primary option to prevent 00:06:39.240 --> 00:06:41.639 transmission to the baby during birth. But there's 00:06:41.639 --> 00:06:43.800 a catch there, isn't there, with resistance? 00:06:44.019 --> 00:06:46.779 There is, unfortunately. Resistance is a growing 00:06:46.779 --> 00:06:49.930 concern. In some areas, like parts of China reportedly, 00:06:50.470 --> 00:06:53.050 resistance rates in group B strep are high enough 00:06:53.050 --> 00:06:55.329 that clindamycin might not be reliable anymore 00:06:55.329 --> 00:06:57.870 for this purpose. So local resistance patterns 00:06:57.870 --> 00:07:00.589 are crucial. The reminder that antibiotic effectiveness 00:07:00.589 --> 00:07:03.930 isn't static. What about, say, dental infections? 00:07:04.509 --> 00:07:06.629 Seems like antibiotics get prescribed for toothaches 00:07:06.629 --> 00:07:09.529 sometimes. They do. And while clindamycin can 00:07:09.529 --> 00:07:12.269 be used for certain dental infections, it's generally 00:07:12.269 --> 00:07:14.170 not considered the best first -line drug for 00:07:14.170 --> 00:07:16.949 routine cases. Why is that? Mainly because other 00:07:16.949 --> 00:07:19.230 antibiotics, like amoxicillin or penicillin, 00:07:19.490 --> 00:07:21.490 are often just as effective for common dental 00:07:21.490 --> 00:07:24.350 infections. But clindamycin carries a significantly 00:07:24.350 --> 00:07:27.110 higher risk of causing clostridioids difficile 00:07:27.110 --> 00:07:30.170 colitis. Ah, C. diff. That's the serious gut 00:07:30.170 --> 00:07:32.290 infection, right? Exactly. It can be quite severe. 00:07:33.149 --> 00:07:36.170 So for many dental situations, the whisk benefit 00:07:36.170 --> 00:07:39.870 balance often favors other antibiotics over clindamycin. 00:07:39.959 --> 00:07:42.279 That's a really important distinction. It's not 00:07:42.279 --> 00:07:44.680 just does it kill the bug, but what are the other 00:07:44.680 --> 00:07:47.939 risks? Okay, so we know what it treats. How does 00:07:47.939 --> 00:07:50.980 it actually stop the bacteria? What's the mechanism? 00:07:51.360 --> 00:07:54.379 The core mechanism is inhibiting bacterial protein 00:07:54.379 --> 00:07:57.100 synthesis. Remember how you said it stops bacteria 00:07:57.100 --> 00:07:59.339 building proteins? Yeah, the bodyguard remover 00:07:59.339 --> 00:08:01.860 analogy. Sort of. It targets the bacterial ribosome 00:08:01.860 --> 00:08:04.639 specifically, the 50S subunit of the ribosome. 00:08:04.959 --> 00:08:07.120 Think of the ribosome as the cell's protein -making 00:08:07.120 --> 00:08:09.819 factory. Okay. Clindamycin binds to that 50S 00:08:09.819 --> 00:08:11.879 subunit and basically throws a wrench in the 00:08:11.879 --> 00:08:15.040 works. It interferes with two critical steps. 00:08:15.660 --> 00:08:18.079 Peptidyl transferase, which is linking the amino 00:08:18.079 --> 00:08:21.319 acid building blocks together, and translocation, 00:08:21.699 --> 00:08:23.540 which is the movement of the growing protein 00:08:23.540 --> 00:08:26.759 chain along the ribosome assembly line. By blocking 00:08:26.759 --> 00:08:28.720 these, it effectively shuts down the production 00:08:28.720 --> 00:08:31.120 of essential proteins the bacteria need to function 00:08:31.120 --> 00:08:34.779 and replicate. So grinding the factory to a halt, 00:08:34.980 --> 00:08:36.899 and you mentioned it's used topically for acne. 00:08:37.039 --> 00:08:39.820 Is the mechanism the same there? Similar. But 00:08:39.820 --> 00:08:42.000 with a couple of nuances. Yes, it reduces the 00:08:42.000 --> 00:08:45.419 population of propionobacterium acnes, now often 00:08:45.419 --> 00:08:48.580 called cutiebacterium acnes, on the skin, which 00:08:48.580 --> 00:08:51.120 is a key bacterium involved in acne breakouts. 00:08:51.220 --> 00:08:54.019 OK. But it also seems to have an anti -inflammatory 00:08:54.019 --> 00:08:56.679 effect by reducing the amount of pro -inflammatory 00:08:56.679 --> 00:09:00.519 free fatty acids on the skin surface. Those contribute 00:09:00.519 --> 00:09:02.659 to the redness and soreness of acne lesions. 00:09:02.919 --> 00:09:05.519 So a dual action on the skin, bacteria and information. 00:09:05.759 --> 00:09:08.120 Right. And an interesting point about the topical 00:09:08.120 --> 00:09:11.220 form. It's usually applied as clindamycin phosphate. 00:09:11.299 --> 00:09:13.659 That's actually inactive. It needs to be hydrolyzed, 00:09:13.860 --> 00:09:16.059 basically broken down by enzymes in the skin, 00:09:16.379 --> 00:09:18.799 to release the active clindamycin. Ah, so it 00:09:18.799 --> 00:09:20.419 gets activated right where it needs to work, 00:09:20.419 --> 00:09:23.080 like a little pro -drug for the skin. Exactly. 00:09:23.139 --> 00:09:25.620 A clever bit of formulation. Okay, that makes 00:09:25.620 --> 00:09:28.700 sense. Now let's trace its path through the body. 00:09:28.879 --> 00:09:32.159 How does it get absorbed? Where does it go? Pharmacokinetics, 00:09:32.320 --> 00:09:34.700 right? Right, pharmacokinetics. So, absorption 00:09:34.700 --> 00:09:38.440 first. Clindamycin is quite lipophilic, fat -loving. 00:09:38.539 --> 00:09:41.440 An important consequence of this, when taken 00:09:41.440 --> 00:09:44.059 orally, is that its absorption isn't really affected 00:09:44.059 --> 00:09:46.340 much by stomach acid levels. So you don't need 00:09:46.340 --> 00:09:48.360 to worry too much about taking it with food or 00:09:48.360 --> 00:09:51.360 antacids messing it up. Generally, its absorption 00:09:51.360 --> 00:09:53.659 rate is pretty good and consistent regardless 00:09:53.659 --> 00:09:57.240 of gastric pH. Bioavailability of the oral forms 00:09:57.240 --> 00:09:59.679 is high. And of course, if you give it intravenously, 00:09:59.879 --> 00:10:02.440 you bypass absorption altogether straight into 00:10:02.440 --> 00:10:05.519 the bloodstream. Which you do for serious infections, 00:10:05.759 --> 00:10:08.139 presumably. Precisely. Faster, more predictable 00:10:08.139 --> 00:10:10.440 levels. Now, absorption in very young infants, 00:10:10.679 --> 00:10:13.600 like neonates, that could theoretically be a 00:10:13.600 --> 00:10:16.080 bit different. How so? Well, their gastric emptying 00:10:16.080 --> 00:10:18.340 and the speed things move through their gut can 00:10:18.340 --> 00:10:21.720 be more variable than in adults. This might potentially 00:10:21.720 --> 00:10:24.159 affect how consistently an oral dose is absorbed, 00:10:24.200 --> 00:10:26.919 but honestly, we lack a lot of specific data 00:10:26.919 --> 00:10:28.940 on this in that age group outside of critical 00:10:28.940 --> 00:10:31.730 care settings. So something to be aware of, but 00:10:31.730 --> 00:10:34.129 maybe not fully quantified in all situations. 00:10:34.289 --> 00:10:35.990 What about the topical stuff? How much of that 00:10:35.990 --> 00:10:39.190 gets absorbed into the body? Very little, actually. 00:10:39.389 --> 00:10:41.889 Systemic absorption from topical clindamycin 00:10:41.889 --> 00:10:44.450 is generally low estimates range from maybe less 00:10:44.450 --> 00:10:47.289 than 1 % up to 4 or 5%. So most of it stays acting 00:10:47.289 --> 00:10:50.470 locally in the skin. OK, good. So once it is 00:10:50.470 --> 00:10:52.889 in the bloodstream, either from an oral dose 00:10:52.889 --> 00:10:56.090 or IV, where does it go? Does it spread out well? 00:10:56.289 --> 00:10:58.929 You mentioned bone earlier. It does distribute 00:10:58.929 --> 00:11:01.169 quite widely. In the blood, a fair bit of it 00:11:01.169 --> 00:11:04.370 binds to plasma proteins, around 77 % in adults, 00:11:04.850 --> 00:11:07.370 mostly to albumin and another protein called 00:11:07.370 --> 00:11:10.629 alpha -1 -acid glycoprotein or AG. Does that 00:11:10.629 --> 00:11:12.970 protein binding affect how it works? Well, only 00:11:12.970 --> 00:11:15.950 the free unbound drug is typically active, but 00:11:15.950 --> 00:11:18.470 the binding influences how it distributes and 00:11:18.470 --> 00:11:21.330 how long it stays around. Interestingly, protein 00:11:21.330 --> 00:11:23.149 binding is lower in newborns and takes until 00:11:23.149 --> 00:11:25.070 about 10 months of age to reach adult levels. 00:11:25.289 --> 00:11:28.840 Ah, another difference in infants. Yes. And pregnancy 00:11:28.840 --> 00:11:32.440 also changes things. Levels of AG and albumin 00:11:32.440 --> 00:11:35.039 tend to decrease during pregnancy, which could 00:11:35.039 --> 00:11:37.460 potentially mean a higher fraction of free active 00:11:37.460 --> 00:11:40.120 clindamycin in pregnant women compared to non 00:11:40.120 --> 00:11:42.240 -pregnant adults. Fascinating how physiology 00:11:42.240 --> 00:11:45.299 changes drug behavior. And it crosses the placenta. 00:11:45.519 --> 00:11:48.259 It does, yes. It passes transplacently, so it 00:11:48.259 --> 00:11:50.500 reaches the fetus. And it's also present in breast 00:11:50.500 --> 00:11:52.419 milk, although usually in quite small amounts 00:11:52.419 --> 00:11:55.580 reported levels are typically between 0 .7 and 00:11:55.580 --> 00:11:58.980 3 .8 micrograms per milliliter. So detectable 00:11:58.980 --> 00:12:02.080 but low, worth discussing with a doctor if pregnant 00:12:02.080 --> 00:12:04.980 or breastfeeding, I imagine. Absolutely. Monitoring 00:12:04.980 --> 00:12:07.340 the infant for potential side effects like diarrhea 00:12:07.340 --> 00:12:10.799 is often recommended. OK. And back to bone. You 00:12:10.799 --> 00:12:13.019 confirmed it gets there. How well? Pretty well. 00:12:13.480 --> 00:12:15.340 Concentrations in bone and joint tissues are 00:12:15.340 --> 00:12:17.700 estimated to be around 30 % of the levels found 00:12:17.700 --> 00:12:19.919 in the blood serum, which is considered good 00:12:19.919 --> 00:12:21.860 penetration for these sites. And is that enough 00:12:21.860 --> 00:12:24.840 to be effective? Often, yes. For antibiotics 00:12:24.840 --> 00:12:26.960 like clindamycin that exhibit time -dependent 00:12:26.960 --> 00:12:29.519 killing, what matters is keeping the concentration 00:12:29.519 --> 00:12:32.340 above the bug's minimum inhibitory concentration, 00:12:32.539 --> 00:12:36.000 MIC. A ratio of bone concentration to MIC of 00:12:36.000 --> 00:12:38.700 around 5 is often targeted, and clindamycin can 00:12:38.700 --> 00:12:41.360 achieve this for susceptible organisms. It's 00:12:41.360 --> 00:12:43.120 also thought to be effective against biofilms. 00:12:43.379 --> 00:12:46.440 Biofilms? Those slimy layers bacteria form. Exactly. 00:12:46.799 --> 00:12:49.100 They make infections much harder to treat, especially 00:12:49.100 --> 00:12:52.200 chronic ones in bone or around implants. Clenomycin's 00:12:52.200 --> 00:12:54.759 activity against biofilms is another plus. Right, 00:12:54.799 --> 00:12:57.159 okay, so it gets absorbed, distributed. How does 00:12:57.159 --> 00:12:59.360 the body get rid of it? Metabolism and elimination? 00:12:59.519 --> 00:13:01.360 Metabolism happens primarily in the liver. The 00:13:01.360 --> 00:13:05.080 main enzyme involved is CYP3A4. Ah, the famous 00:13:05.080 --> 00:13:09.279 CYP enzyme system. Indeed. CYP3A4 breaks clindamycin 00:13:09.279 --> 00:13:11.500 down mainly into clindamycin sulfoxide, which 00:13:11.500 --> 00:13:13.679 is the major metabolite, and also a minor one 00:13:13.679 --> 00:13:16.220 called endomethyl clindamycin. Another related 00:13:16.220 --> 00:13:19.159 enzyme, CYP3A5, also contributes a bit to making 00:13:19.159 --> 00:13:21.639 the sulfoxide metabolite. And does anything affect 00:13:21.639 --> 00:13:25.129 these enzymes, like pregnancy maybe? Yes, pregnancy 00:13:25.129 --> 00:13:30.070 significantly boosts CYP3A4 activity. So potentially, 00:13:30.330 --> 00:13:32.450 clindamycin might get metabolized and cleared 00:13:32.450 --> 00:13:34.870 faster in pregnant individuals. Interesting. 00:13:35.169 --> 00:13:37.370 And then elimination. How long does it stick 00:13:37.370 --> 00:13:39.669 around? The elimination half -life of the active 00:13:39.669 --> 00:13:42.450 drug in adults is typically around three hours. 00:13:43.110 --> 00:13:45.789 So half of it is gone from the blood in about 00:13:45.789 --> 00:13:48.070 three hours. Relatively short. Comparatively, 00:13:48.269 --> 00:13:51.190 yes. which influences dosing schedules, of course. 00:13:51.289 --> 00:13:53.809 And pharmacodynamics. You mentioned time -dependent 00:13:53.809 --> 00:13:55.750 killing. Right. That means its effectiveness 00:13:55.750 --> 00:13:58.750 is more related to the duration the drug concentration 00:13:58.750 --> 00:14:01.830 stays above the MIC rather than how high the 00:14:01.830 --> 00:14:04.470 peak concentration gets. Sustained pressure on 00:14:04.470 --> 00:14:07.649 the bacteria is key. And for biofilms? For biofilms, 00:14:07.909 --> 00:14:10.330 the overall exposure over time, often measured 00:14:10.330 --> 00:14:13.529 as the AUC MIC ratio, area under the curve over 00:14:13.529 --> 00:14:16.370 MIC, seems to be more important. Clindamycin 00:14:16.370 --> 00:14:18.190 generally performs well by these measures, too. 00:14:18.330 --> 00:14:20.570 Okay, that paints a clear picture of its journey 00:14:20.570 --> 00:14:23.090 in action. Let's switch tracks slightly to manufacturing. 00:14:23.549 --> 00:14:25.990 How is clindamycin actually made? It's semi -synthetic, 00:14:26.029 --> 00:14:28.450 you said? That's right. It starts with lincomycin, 00:14:28.789 --> 00:14:31.769 which is naturally produced by a bacterium, streptomyces 00:14:31.769 --> 00:14:35.529 lincinensis. Then, through chemical modification, 00:14:35.789 --> 00:14:37.950 that chlorination step we mentioned, it's converted 00:14:37.950 --> 00:14:41.210 into clindamycin. So part nature, part chemistry 00:14:41.210 --> 00:14:44.350 lab. Pretty much. And groups like the iMark Group 00:14:44.350 --> 00:14:47.090 actually publish detailed reports on the manufacturing 00:14:47.090 --> 00:14:49.309 process. They cover things like the specific 00:14:49.309 --> 00:14:52.230 unit operations, quality control tests, mass 00:14:52.230 --> 00:14:54.990 balance calculations, raw material requirements, 00:14:55.409 --> 00:14:58.029 even plant layout and machinery needed. Wow. 00:14:58.149 --> 00:15:00.730 Quite detailed. Sounds like a complex industrial 00:15:00.730 --> 00:15:03.649 process. It is. And crucially, it has to be done 00:15:03.649 --> 00:15:06.710 according to strict quality standards, good manufacturing 00:15:06.710 --> 00:15:10.110 practice, or GMP. GMP. We hear that a lot with 00:15:10.110 --> 00:15:12.919 pharmaceuticals. As you should. Regulatory bodies 00:15:12.919 --> 00:15:15.059 like the Medicines Evaluation Board in the Netherlands, 00:15:15.240 --> 00:15:17.820 which assess some generic versions, rigorously 00:15:17.820 --> 00:15:20.019 inspect manufacturing sites to ensure they comply 00:15:20.019 --> 00:15:22.559 with GMP for both the active substance and the 00:15:22.559 --> 00:15:25.100 final drug product. It covers everything. Cleanliness, 00:15:25.519 --> 00:15:27.700 procedures, documentation, training. Ensuring 00:15:27.700 --> 00:15:30.740 consistency and safety in every batch makes sense. 00:15:31.700 --> 00:15:34.000 Are there environmental considerations in making 00:15:34.000 --> 00:15:36.679 antibiotics like clindamycin? There's growing 00:15:36.679 --> 00:15:39.110 concern about that, isn't there? A very significant 00:15:39.110 --> 00:15:42.129 concern, yes. The potential for antibiotic residues 00:15:42.129 --> 00:15:45.090 in manufacturing waste to contribute to antimicrobial 00:15:45.090 --> 00:15:48.610 resistance, or AMR, in the environment is a major 00:15:48.610 --> 00:15:51.710 issue. So what's being done? Well, industry groups 00:15:51.710 --> 00:15:54.470 like the AMR Industry Alliance have established 00:15:54.470 --> 00:15:57.070 frameworks outlining minimum expectations for 00:15:57.070 --> 00:15:59.629 manufacturers. This includes complying with local 00:15:59.629 --> 00:16:02.090 environmental laws, having strong environmental 00:16:02.090 --> 00:16:05.529 health and safety, EHS programs, characterizing 00:16:05.529 --> 00:16:08.149 wastewater, and ensuring effective treatment 00:16:08.149 --> 00:16:10.529 to remove active antibiotic compounds before 00:16:10.529 --> 00:16:12.889 discharge. Treating the factory's wastewater 00:16:12.889 --> 00:16:15.509 properly. Critically important. It also involves 00:16:15.509 --> 00:16:17.730 responsible management of other waste streams, 00:16:17.929 --> 00:16:20.029 like the biomass left over from fermentation 00:16:20.029 --> 00:16:22.809 processes, if applicable, and ensuring monitoring 00:16:22.809 --> 00:16:25.419 equipment is properly maintained. These align 00:16:25.419 --> 00:16:27.379 with principles from groups like the Pharmaceutical 00:16:27.379 --> 00:16:31.000 Supply Chain Initiative, or PSCI. So a push for 00:16:31.000 --> 00:16:33.899 greener, more responsible manufacturing to help 00:16:33.899 --> 00:16:37.940 combat resistance. Good to hear. Now what about 00:16:37.940 --> 00:16:40.639 legal issues or controversies specifically tied 00:16:40.639 --> 00:16:43.340 to clindamycin? We touched on labeling. Right, 00:16:43.440 --> 00:16:45.600 the focus on clear labeling to minimize errors 00:16:45.600 --> 00:16:48.879 is ongoing. But the biggest controversy, or perhaps 00:16:48.879 --> 00:16:51.460 challenge, is the one we keep circling back to. 00:16:52.240 --> 00:16:54.559 Antibiotic resistance. It just keeps coming up. 00:16:54.740 --> 00:16:56.879 Because it's so critical. We mentioned the rising 00:16:56.879 --> 00:16:59.440 resistance in group B strep in some places, but 00:16:59.440 --> 00:17:01.519 it's happening with other bacteria too, limiting 00:17:01.519 --> 00:17:04.460 clindamycin's usefulness over time. It's a constant 00:17:04.460 --> 00:17:06.900 battle. A global health threat. What about safety 00:17:06.900 --> 00:17:09.619 controversies beyond resistance? The main one, 00:17:09.660 --> 00:17:12.200 as we discussed regarding dental use, is the 00:17:12.200 --> 00:17:14.819 elevated risk of clostridioids, difficult infection 00:17:14.819 --> 00:17:18.460 CDI. Compared to many other antibiotics, clindamycin 00:17:18.460 --> 00:17:20.500 is more frequently associated with triggering 00:17:20.500 --> 00:17:23.480 C. diff. Even short courses or single doses have 00:17:23.480 --> 00:17:26.140 been implicated sometimes. That's a really significant 00:17:26.140 --> 00:17:29.200 downside to whey, a serious potential harm. It 00:17:29.200 --> 00:17:31.880 absolutely is. And it's why careful consideration 00:17:31.880 --> 00:17:34.339 of whether it's truly the best option, especially 00:17:34.339 --> 00:17:36.900 when effective alternatives with lower CDI risk 00:17:36.900 --> 00:17:39.779 exist, is so important in clinical practice. 00:17:40.000 --> 00:17:42.630 Definitely. Any major drug interaction issues 00:17:42.630 --> 00:17:44.789 we should highlight? You mentioned the CYP enzymes. 00:17:44.970 --> 00:17:48.410 Yes, those CYP3A4 interactions are key. Drugs 00:17:48.410 --> 00:17:51.789 that induce or speed up CYP3A4 like the antibiotic 00:17:51.789 --> 00:17:54.970 rifampicin or potentially even flucloxacillin 00:17:54.970 --> 00:17:58.069 can lower clindamycin levels in the body, possibly 00:17:58.069 --> 00:18:00.230 making it less effective. Okay, so taking it 00:18:00.230 --> 00:18:02.750 with rifampicin might stop it working properly. 00:18:03.130 --> 00:18:05.190 What about the opposite? Drugs that inhibit or 00:18:05.190 --> 00:18:08.390 slow down CYP3A4 can cause clindamycin levels 00:18:08.390 --> 00:18:10.730 to rise, increasing the risk of side effects. 00:18:10.970 --> 00:18:13.990 A very relevant example now is Retonavir, which 00:18:13.990 --> 00:18:16.809 is a component of the COVID -19 antiviral Paxlovid. 00:18:16.910 --> 00:18:19.410 Ah, so taking clindamycin while on Paxlovid could 00:18:19.410 --> 00:18:21.849 lead to problems. It could potentially lead to 00:18:21.849 --> 00:18:24.710 higher clindamycin exposure, yes. So a careful 00:18:24.710 --> 00:18:27.230 review of all medications a patient is taking 00:18:27.230 --> 00:18:29.829 is absolutely essential before starting clindamycin 00:18:29.829 --> 00:18:31.990 to avoid these kinds of interactions. Crucial 00:18:31.990 --> 00:18:33.970 safety check. Okay, let's touch on the economics. 00:18:34.190 --> 00:18:37.069 Is clindamycin a big market? Well, market reports, 00:18:37.390 --> 00:18:40.210 like those from iMark, do track clindamycin phosphate 00:18:40.210 --> 00:18:42.869 prices and demand, suggesting it's an active 00:18:42.869 --> 00:18:46.049 market segment. The existence of multiple generic 00:18:46.049 --> 00:18:48.930 formulations, like clindamycin TAVA or clindamycin 00:18:48.930 --> 00:18:51.269 doubly pharma, mentioned in some European sources, 00:18:51.730 --> 00:18:54.150 points to it being generally available and likely 00:18:54.150 --> 00:18:57.490 cost -effective as a drug substance itself. So 00:18:57.490 --> 00:19:00.910 the drug cost might be reasonable. Likely, yes, 00:19:01.150 --> 00:19:03.309 due to generic competition. But you also have 00:19:03.309 --> 00:19:06.079 to factor in the broader economics. The cost 00:19:06.079 --> 00:19:08.319 savings, if it successfully prevents a costly 00:19:08.319 --> 00:19:11.339 surgical site infection, for example, but also 00:19:11.339 --> 00:19:13.660 the potential costs incurred if it causes a serious 00:19:13.660 --> 00:19:16.240 side effect like C. diff infection, which requires 00:19:16.240 --> 00:19:18.259 treatment and hospitalization. Right, it's a 00:19:18.259 --> 00:19:20.279 balance, the cost of the drug versus the cost 00:19:20.279 --> 00:19:22.420 of the illness it treats or potentially causes. 00:19:22.579 --> 00:19:25.119 Exactly, a health economic assessment. Okay. 00:19:25.309 --> 00:19:27.849 Lastly, let's think about its cultural influence, 00:19:27.950 --> 00:19:30.670 if any. How does it fit into the wider medical 00:19:30.670 --> 00:19:33.650 and societal landscape? Well, cultural influence 00:19:33.650 --> 00:19:36.289 might be a strong term, but its usage patterns 00:19:36.289 --> 00:19:38.650 are definitely shaped by prevailing medical culture 00:19:38.650 --> 00:19:41.490 and guidelines. We see recommendations from bodies 00:19:41.490 --> 00:19:45.630 like the CDC in the US, ECDC in Europe, SHB, 00:19:46.190 --> 00:19:50.470 IDSA, NICE in the UK. All influencing when clindamycin 00:19:50.470 --> 00:19:52.990 is recommended for things like surgical prophylaxis, 00:19:53.029 --> 00:19:55.789 preventing group B strep, or preventing endocarditis 00:19:55.789 --> 00:19:58.630 in certain patients. So the expert guidelines 00:19:58.630 --> 00:20:01.589 really steer its use. Do prescribing habits differ 00:20:01.589 --> 00:20:03.650 much by region? Historically, there might have 00:20:03.650 --> 00:20:06.289 been more regional variation. But some sources 00:20:06.289 --> 00:20:08.529 suggest that with increased global awareness 00:20:08.529 --> 00:20:11.029 of antibiotic stewardship principles, some of 00:20:11.029 --> 00:20:13.009 those geographical differences in prescribing 00:20:13.009 --> 00:20:15.089 might actually be decreasing now. There's more 00:20:15.089 --> 00:20:17.549 standardization. A move towards more evidence 00:20:17.549 --> 00:20:19.950 -based, globally conscious prescribing. That's 00:20:19.950 --> 00:20:21.930 positive. What about patient awareness? How do 00:20:21.930 --> 00:20:24.259 people learn about this drug? Patient information 00:20:24.259 --> 00:20:26.759 resources are key here. Websites like Medline 00:20:26.759 --> 00:20:29.420 Plus or Medical News Today provide accessible 00:20:29.420 --> 00:20:31.660 information for the public. They explain what 00:20:31.660 --> 00:20:34.119 it's for, list common and serious side effects, 00:20:34.319 --> 00:20:37.299 and give crucial advice like taking oral capsules 00:20:37.299 --> 00:20:39.700 with a full glass of water and staying upright 00:20:39.700 --> 00:20:42.319 for a bit to prevent throat irritation. And reminding 00:20:42.319 --> 00:20:44.799 people to finish the whole course, I bet. Absolutely. 00:20:45.079 --> 00:20:47.240 Patient education is vital for effective and 00:20:47.240 --> 00:20:50.180 safe antibiotic use. These resources empower 00:20:50.180 --> 00:20:51.779 patients to understand their treatment better. 00:20:51.900 --> 00:20:54.710 Definitely. And one last intriguing point that 00:20:54.710 --> 00:20:57.970 came up was potential future uses outside of 00:20:57.970 --> 00:21:00.170 infections. Something about cancer. Yes, that 00:21:00.170 --> 00:21:02.950 was a fascinating snippet. There's ongoing research 00:21:02.950 --> 00:21:05.470 looking into derivatives of clindamycin chemically 00:21:05.470 --> 00:21:08.150 related molecules as potential anti -tumor agents. 00:21:08.430 --> 00:21:11.470 Really? How would that even work? The mechanisms 00:21:11.470 --> 00:21:13.950 aren't fully clear yet and seem distinct from 00:21:13.950 --> 00:21:16.849 its antibacterial action. But early research 00:21:16.849 --> 00:21:19.029 suggests some of these related compounds might 00:21:19.029 --> 00:21:21.839 inhibit cancer cell growth. It's still very much 00:21:21.839 --> 00:21:24.900 in the research phase, of course. Wow. But the 00:21:24.900 --> 00:21:27.660 idea of repurposing an old antibiotic family 00:21:27.660 --> 00:21:29.880 for something completely different like cancer 00:21:29.880 --> 00:21:32.259 therapy, that's quite something. It really is. 00:21:32.480 --> 00:21:34.759 It shows that even well -established drugs might 00:21:34.759 --> 00:21:37.019 hold secrets or potential we haven't fully unlocked 00:21:37.019 --> 00:21:39.730 yet. A surprising twist. So we've covered quite 00:21:39.730 --> 00:21:42.690 a journey today from its origins and approvals. 00:21:42.789 --> 00:21:44.670 Through its many clinical uses, especially as 00:21:44.670 --> 00:21:46.789 an alternative for penicillin -allergic patients 00:21:46.789 --> 00:21:49.450 and its effectiveness in tricky spots like bone. 00:21:49.589 --> 00:21:52.529 How it actually works by stopping protein production 00:21:52.529 --> 00:21:56.089 in bacteria, its path through the body. The manufacturing 00:21:56.089 --> 00:21:59.150 process and the importance of GMP and environmental 00:21:59.150 --> 00:22:01.089 stewardship. And the significant issues around 00:22:01.089 --> 00:22:04.069 resistance, the C. differis, and potential drug 00:22:04.069 --> 00:22:07.329 interactions. And finally, its place in the market, 00:22:07.329 --> 00:22:11.430 and maybe, just maybe, a future beyond fighting 00:22:11.430 --> 00:22:14.109 bacteria. So wrapping up, clindamycin remains 00:22:14.109 --> 00:22:16.430 a really valuable tool in the antibiotic arsenal, 00:22:16.589 --> 00:22:19.269 versatile, effective for specific scenarios like 00:22:19.269 --> 00:22:22.089 bone infections or in penicillin allergies. But 00:22:22.089 --> 00:22:24.910 its use demands careful consideration of resistance 00:22:24.910 --> 00:22:28.549 trends and that significant C. diff risk. Absolutely. 00:22:28.849 --> 00:22:31.710 And that potential future research into anti 00:22:31.710 --> 00:22:34.410 -tumor activity leaves us with a pretty interesting 00:22:34.410 --> 00:22:36.849 thought, doesn't it? Given the immense challenge 00:22:36.849 --> 00:22:39.930 of rising antibiotic resistance, how vital is 00:22:39.930 --> 00:22:42.289 it that we explore every avenue for existing 00:22:42.289 --> 00:22:45.549 drug families? Does finding new uses, like potentially 00:22:45.549 --> 00:22:48.289 in cancer, become even more critical as resistance 00:22:48.289 --> 00:22:51.490 limits their original roles? That's a fascinating 00:22:51.490 --> 00:22:53.670 question to ponder. Balancing the stewardship 00:22:53.670 --> 00:22:56.109 of current antibiotics against the urgent need 00:22:56.109 --> 00:22:58.650 for new therapeutic strategies across medicine 00:22:58.650 --> 00:23:00.789 really makes you think. It does indeed. Well, 00:23:00.789 --> 00:23:02.690 that's all the time we have for this deep dive 00:23:02.690 --> 00:23:04.789 on clindamycin. Thanks for joining us. Thanks 00:23:04.789 --> 00:23:05.210 for listening.