Transcription
Hey guys, it's Médicos. Is perfection Alice? One more time, continuing our playlist about bleeding and coagulation disorders. So we have talked about anti-platelets before, okay? And we have talked about the fibrinolytics before. Cool. Anti-platelets include aspirin and the P2Y12 receptor inhibitors such as clopidogrel, the GPIIb/IIIa inhibitors such as the F6M F, and the phosphodiesterase inhibitors such as dipyridamole. Angeles's all got it, okay?
Then we talked about tPA drugs, as streptokinase, alteplase. Let's say aspirin here. What's the antidote of aspirin? There is no such thing; it doesn't exist. Anyone who tells you otherwise is what's known as, like, a liar, until the moment of the recording of this video. tPA, however, is there an antidote to tPA? And the answer is yes, called anti-fibrinolytic therapy, such as the famous tranexamic acid. And in the next video, we'll talk about aminocaproic acid. What was the goal of tPA? To destroy the clot. What is the goal of tranexamic acid and aminocaproic acid? To stop the stupid tPA from destroying the clot that took us a long time to build. Okay, so they prevent the tPA from causing thrombosis; in other words, they preserve the clot. And this is the topic of today's video, and let's get started. [Music]
As you know, hemostasis is the process of preventing blood loss by forming a clot, and it has many steps: basic instruction, platelet plug, and coagulation, than fibrinolysis. So aspirin works on preventing lysis; tPA works on destroying that clot, leading to fibrinolysis. Anti-fibrinolytic therapy, which is the topic of today's video, will save and preserve and maintain the clot and prevent the fibrinolysis. Here's the whole story. Enjoy yourself. Ease constriction, platelet plug, which is primary hemostasis, then secondary hemostasis, the coagulation cascade, the fibrin mesh work formed, traps the red blood cell, clot contracts. tPA does work; tPA does fibrinolysis, but with the medication of today's video, tPA is history; fibrinolysis is not going to happen. We are going to preserve this fibrin mesh work. In other words, if your doctor is stupid and gave you lots of tPA for no reason, and he realized he made a bad mistake, he can give you tranexamic acid or aminocaproic acid to reverse this mistake and preserve the fibrin mesh, or lest you should bleed to death.
Let's talk about fibrinolysis. So what's the enzyme? It's called plasmin. Plasmin comes from what? From plasminogen. What does plasmin do? Degrades the fibrinogen and the fibrin. Degrades fibrinogen into fibrin degradation products. Degrades fibrin into fibrin degradation products. Degrades the stabilized fibrin into the dimer. And we have talked about all of this before in previous videos. Plasmin is crazy; don't leave it alone. Put it in an inactive precursor form called plasminogen. And you need tPA to convert the plasminogen into the active plasmin. Plasmin will destroy the clot. So tPA activates plasminogen to plasmin to destroy the clot. Anti-fibrinolytic therapy will preserve the plasminogen; they will prevent the formation of plasmin; they will maintain the clot. Fibrinolysis: plasminogen to plasmin destroys fibrin, degradation products, and fibrinogen into fibrin degradation products, and stabilized fibrin into D-dimer. With the anti-fibrinolytic therapy, plasmin is history. We'll keep plasminogen inactive; therefore, we're not gonna degrade the fibrinogen, we're not gonna degrade the fibrin, we're not gonna degrade the stabilized fibrin, and therefore we're gonna preserve the clot. Thank you so much. Tranexamic acid and aminocaproic acid. So plasminogen, plasmin destroys the clot, or dissolves the fibrin. This was the fibrin to fibrin degradation products and dissolve the stabilized fibrin into the D-dimer. Okay, let's prevent fibrinolysis. You can prevent it at this moment by plasminogen activator inhibitors; they are already in your body, or you can give therapy drugs from the outside because you are stupid and you gave too much tPA, or you gave tPA for no reason. So we use anti-fibrinolytic therapy called aminocaproic acid or tranexamic acid to prevent the conversion of plasminogen to plasmin, to prevent the dissolution of fibrin into fibrin degradation products. Cool. About tPA: tPA is the exact opposite; tPA causes fibrinolysis. So tPA is the exact opposite of anti-tPA, which makes perfect sense. And in previous videos, I've told you if you want to prevent or inhibit plasmin, there is the alpha-2-antiplasmin. If you wanna prevent this step, it's called thrombin-activatable fibrinolysis inhibitor, and this is activated by thrombin. Thrombin is acting in its self-interest because thrombin is the one that formed the clot; if you decided to tamper with it, he's gonna prevent you. For the last time: plasminogen to plasmin. HOH stimulates this process: tPA or kinase, etc. Who inhibits this process? Plasminogen activator inhibitor from the inside; anti-fibrinolytic therapy from the outside, such as aminocaproic acid and tranexamic acid. Many authors argue that tranexamic acid is more potent than the aminocaproic acid.
So this slide is the foundation to what's coming next. Anti-fibrinolytic therapies are anti-tPA; they include aminocaproic acid, tranexamic acid; they prevent fibrinolysis; yep, they are anti-tPA; therefore, they prevent the conversion of plasminogen to plasmin; therefore, it's like this is how they do it; therefore, they preserve the fibrin mesh work and reduce the bleeding. Makes perfect sense; it follows logically. Tranexamic acid, available oral or IV. Anti-fibrinolytic therapy inhibits that conversion of plasminogen to plasmin; in other words, it inhibits the activation of plasminogen to plasmin; in other words, and inhibits fibrinolysis; that's why we called anti-fibrinolytic therapy, duh. Why do you use it? To prevent excessive bleeding because it preserves the clot. Okay, so what are the indications? Bleeding: so major trauma, surgery, postpartum hemorrhage, heavy menses, especially in von Willebrand disease, or von Willebrand disease, to be accurate, dental procedures, and nosebleeds. So tranexamic acid is loved by the surgeon, by the OBGYN, by the dentist, by the ENT guy or gal. Side-effects: if you are going to prevent bleeding, you're gonna cause clotting. Sorry, actions have consequences in life; there are no solutions, only trade-offs. So blood clots, big time, allergy, and some vision changes. Tranexamic acid is handled by the kidney; don't forget this if you are a sophisticated student. Oh, right, tranexamic acid prevents the conversion of plasminogen to plasmin; how? Competitive inhibition. Alright, if you have a patient who has hemophilia and there's a risk of bleeding during a dental procedure, which could be tooth extraction or even dental surgery, you can give tranexamic acid or aminocaproic acid. Never, ever, ever give antifibrinolytics to control hematuria; this is called stupid because they can cause clots, and the lumen of your ureter, for example, is narrow; if you form clots in the ureter, you're a horrible doctor. Oh, but I had some good intentions; I wanted to cure the hematuria, not with antifibrinolytics. Okay, okay. Severe case of DIC with confirmed hyperfibrinolysis, you can give antifibrinolytics. Beware, these antifibrinolytics may increase the risk of thrombosis; as you know, if this happens, give heparin. Antifibrinolytics can be used in von Willebrand disease adjunctively; it's not the main therapy, but it helps for mucosal bleeding or procedures. Since tranexamic acid is handled by the kidney, it's contraindicated in patients with severe renal impairment. And I had a video about the five stages of chronic kidney disease and a mnemonic about how to remember them and have to remember the GFR number for each; it's available on my channel. What are other contraindications? Allergy, of course; active thromboembolic disease because these guys will lead to clots; history of thromboembolism for the same freakin' reason; and history of seizures. So here is everything you need to know about tranexamic acid in brief. Not boxers. If you love medical mnemonics, you will love this website called Picmonic; check the link in the description below. Thank you so much for watching; please subscribe and join the tribe in the bell to get notified. You can support this channel by Patreon, and you'll send you my notes. Thank you, until next time.