How does Aspirin work? Antiplatelet medication via COX-1 pathway.
Welcome to another episode of drug chug and today we’ll talk about aspirin and how it works plus some pharmacology so let’s get right into it a quick breakdown of everything in this video first we’ll talk about how platelets work and then we’ll get into aspirin the dosing and mechanism of action then we’ll talk about the side effects then we’ll talk about an aspirin
Combination product and then the summary and then a short quiz as always at the end to see what we retained so first we need to learn how platelets actually work so that we could understand why and how aspirin is beneficial to us so first here we have a very calm platelet and these are just circulating throughout our blood and once they send some tissue injury they
Start to activate so they could sense like a paper cut or let’s say you know you fell and you scraped your knee or whatever it is and they sense that tissue damage they start becoming a mad platelet they start becoming aggressive and once they’re in this active aggressive form there are two sensors that we look for we have thromboxane 2 and adp remember these
Two and these two sensors cause platelet recruitment and aggregation and that just means that the angry platelets all coming together as like one team and this is referred to as a platelet plug and this is a very weak blood clot all of this is happening and they’re recruiting together we also have something called the coagulation cascade which is just a bunch of
Steps that eventually lead up to fibrin being made and fibrin is literally just a fiber or like a string and what fibrin does is it intertwines with this platelet plug causing a fibrin clot so we have all of these mad platelets and all of this fibrin sticking together and this is a pretty strong blood clot so the important thing to take from all of this is that
There are two chemical signals we have from saying a2 and adp that caused this platelet aggregation giving us our platelet plug and then the coagulation cascade making fibrin so that we could have a fibrin clot now that we know how platelets actually work let’s talk about aspirin so aspirin has two doses we have our baby aspirin dose which is 81 milligrams and
Then we have our normal dose which is 325 milligrams for now we’re gonna focus on the baby aspirin because we’re talking about platelets so it all starts with arachidonic acid and this is produced through our prostaglandin pathway and essentially we have an enzyme called cox-1 which converts arachidonic acid to thromboxane a2 and remember thromboxane a2 was one
Of those chemical signals that we need to pay attention to now what thromboxane a2 does is it causes the platelet aggregation so when aspirin is taken it blocks cox-1 which stops thromboxane a2 which stops the platelet aggregation and what’s cool is you only need 81 milligrams to fully block that cox-1 pathway now because of this the fda has approved aspirin to
Prevent and treat heart attack and stroke patients and again it’s because it blocks the cox one pathway which stops blood from clotting so i also want to note that if a patient takes a regular dose of a 325 milligrams ablett well what happens is it not only blocks cox 1 but it can also block the cox-2 pathway and the cox-2 pathway has to do with more of the pain
Inflammation fever and some other conditions but we’ll talk about that more in the nsaid video all right so let’s talk about some of the side effects that aspirin can cause so we said that it can inhibit cox 1 well cox one is also responsible for having protective factors in our stomach so it produces gastric mucus and helps with cell turnover so if we block coq
Swan we also block these protective factors of the stomach so an inhibiting cox-1 we could see things that aren’t too severe like dyspepsia which is just difficulty digesting food and we might see upper abdomen pain but if it gets a little bit more severe we could have peptic ulcers or gi ulcerations in our stomach and the reason for that is if we don’t have that
Protective mucosal layer then the stomach acid will keep attacking our stomach wall and they’ll start producing these ulcers and if it gets severe enough and this is the most severe it could actually lead to gastrointestinal bleeding and this is where we’ll actually have bleeding of the stomach and one thing to note is that it’s not only in the stomach that we
Might see bleeding we might see non gi bleeding as well and that’s because we’re blocking thromboxane a2 not only in the stomach but essentially throughout our entire body and another side effect of aspirin to take note of is tinnitus and this is the ringing of the ear and this is dose dependent just like all our other nsaids but if we think about it tinnitus is
Very rare when we’re dosing aspirin for antiplatelet effects right because we said that aspirin has a full coxswain blocking ability when we give that eighty one milligram baby dose of aspirin so tinnitus should be very rare in these patients because we’re giving such a low dose but if we give them a bigger dose like a regular 325 milligrams ablett it does not
Provide better cardiovascular protection we get that full cardiovascular protection at the small dose and one thing i want to make clear is that yes we say baby aspirin but you’d be shocked how many patients would come in thinking that it’s for actual babies and it’s not even though aspirin is approved for children over the age of three we want to avoid giving
Aspirin to any child or teenager because of the risk of raise syndrome and race a dream is a very rare complication that happens that we’ve seen with aspirin and what happens is we have a child that suffers from confusion and then they’ll have swelling in their brain and then it’ll cause liver damage so this is a very serious side effect that we might see in
Children and teenagers and we typically see it when teenagers are recovering from chickenpox or if they had the flu so always avoid giving aspirin to these patient population so we do have one combo product of aspirin and it’s actually called agra knox and here in a single dose we’ll have 25 milligrams of aspirin and 200 milligrams of diaper animal and here we
Could see that we have to take it twice a day so for the aspirin part we already said that it hibbett sox 1 and that stops thromboxane a2 which was one of the signaling pathways for platelet aggregation so on the diaper adamo slide it blocks the response to adp and if you remember from the beginning that was the second messenger that we need to pay attention to
So this combination product blocks both from box and a2 and it also blocks adp so this combination medication is used only for secondary stroke prevention meaning our patient has already had a stroke and we’re just trying to prevent another stroke from occurring this medication comes in an extended release form which means that we cannot crush up the capsule and
Whenever we have a stroke patient there is a good chance that they’re gonna have difficulty swallowing so this might not be a good option for them because they need to swallow that capsule hole even though this is an extended release product you still have to take it twice a day and if we look at the dosing we have 25 milligrams of aspirin so if we take it twice
A day it bumps up to 50 milligrams every day which is a pretty good dose to stop that platelet aggregation one good counselling point here is that the diaper animal can cause vasodilation which leads to headache and typically we’ll see how they can one out of three patients so it’s very problematic but one thing we have to tell our patients is that it does get
Better over time so let’s take a quick summary and then a short quiz so first we talked about how platelets work we said we had a completely until it senses a cut or scrape and then it becomes a mad platelet and then this mad platelet starts to aggregate and recruit so that there’s a group of them and this is done by thromboxane a2 and adp so then we talk about
Aspirin and we said how aspirin is a cox-1 inhibitor so it blocks this enzyme which stops thromboxane a2 which stops aggregation and then we also talked about a combination product of aspirin and die paradigm oh and the brand name was agra knox and we said how this has both aspirin and i private but all which causes thromboxane a2 and adp to be blocked to fully
Stop aggregation and we said aspirin it has an 81 milligram dose that’s our baby aspirin and higher doses can cause ulcers and then also higher the dose we could have tinnitus because it is an n set for agri knocks we said that it is two medications in one we have 25 milligrams of aspirin and 200 milligrams of type i read them all and this is a twice a day dosing
And it’s extended-release meaning you can’t crush it up and then also one big side effect is one in three patients will experience headaches but it does get better and there you go that’s everything so let’s take a short quiz to see what we retained so question one how many milligrams of aspirin fully inhibits the cox-1 pathway question two which pathway primarily
Mediates the pain and inflammation pathway question three what is the most severe side effect from taking aspirin question 4 what is the right strength combination for agri knocks you
Transcribed from video
How does Aspirin Work? (+ Pharmacology) By Drug Chug
