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How Do Nitrates Work? (Nitroglycerin)

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How do Nitrates (Nitroglycerin) Work? These direct nitrates are vasodilators that increase cGMP which causes veins to dilate . This causes an increase in oxygen supply to the heart, which reduces angina (chest pain).

Hello and welcome to another drug drug episode and today we’ll talk about nitrates and how they work plus some pharmacology let’s get right into it so here’s a breakdown of everything in this video there will be time stamps down below and a short quiz at the end to see what we retained so to understand how nitrates work we need a quick overview and to do that

We kind of need to look at the heart so the first thing we need to know is something called angina pectoris which literally means chest pain and here we could see a patient holding their heart and they’re having that chest pain and that’s actually caused by the heart so let’s take a look how so here we have the heart and essentially there’s a balance between the

Oxygen supplied and the oxygen demanded by the heart because remember the heart is a muscle so as it keeps pumping and if it pumps harder and faster it’s going to need more and more oxygen so the issue with angina pectoris is there is a imbalance of oxygen supply and oxygen demand meaning the heart is demanding more oxygen than it can actually pump to itself so

Let’s take running for example you know if we run obviously our heart rate goes up and the demand for oxygen for not only the heart but essentially the whole body will go up so the issue is that the oxygen supply isn’t getting to the heart fast enough or efficiently enough and when this happens when there is less oxygen supply and more oxygen demand right then

We have something called ischemia which literally means not enough oxygen and that could damage our heart but the heart knows that it’s not having enough oxygen and then that’s when we’ll see patients have angina pectoris because the heart is literally hurting because of the lack of oxygen and they feel that chest pain so now that we know a little bit about the

Back story of having chest pains let’s talk about nitrates and how they work so here we have our first three nitrates these are the most common we have something called nitroglycerin which is the most common and then we have longer acting nitrates which we’ll talk about in detail later called isosorbide mononitrate and isosorbide dinitrate so since we said the

Issue with angina that chest pain was the lack of oxygen supply to oxygen demand what we need to do is increase the oxygen supply right if we need more oxygen we got to figure out a way to allow the heart to have more oxygen and in a nutshell that’s what nitrates do they allow more oxygen to go to the heart so here we see we have veins and arteries that lead

To and from the heart and remember oxygen is carried through blood cells right your blood and your hemoglobin inside the actual blood cell holds oxygen so the way nitrates work is they actually dilate the veins leading to the heart and this is also called preload meaning before the blood supply and if we increase the preload if we dilate those veins we allow

More blood to easily flow in with oxygen so now we know that nitrates dilate the veins allowing more blood and more oxygen to reach the heart so how does that actually happen right so if we have a patient like this one here and we give them nitroglycerin essentially what happens is that medication gets absorbed and nitric oxide which is part of the medication

Is released so that nitric oxide in our body will allow the formation of something called cyclic gmp or abbreviated as c gmp and cyclic gmp in our body allows for smooth muscles to relax and smooth muscles are like our veins and arteries now when the smooth muscles relax we get that vasodilation and because of that we see an improved blood supply and we have an

Increased oxygen supply to meet the demand so essentially again we’re just increasing that supply to the heart so that it has efficient oxygen so when do we actually use these nitrates well there’s two realistic possibilities in our patients so we have something called acute angina meaning they have severe chest pain and we need to treat their chest pain right

Now and we use the nitroglycerin for that it’s very quick acting it dissolves under the tongue and it gives very fast relief and on the other side we have chronic angina and here we use our other preventative measures we use the isosorbide mononitrate or dinitrate and again this is more of a preventative cause these last a lot longer these last for 12 hours and

The reason a patient may need these drugs is that their blood vessels may narrow for example a patient can have coronary artery disease we could have plaque buildup in the veins leading less and less blood flow to the heart which could lead to the ischemia and the chest pain so let’s dive a little bit deeper into the actual drugs and the dosing so to treat the

Acute angina we said we used nitroglycerin the brand name is nitrostat meaning immediate use right so nitrostat and here we have the dosing of 0.3 to 0.6 milligrams sublingual every 5 minutes again we’re using this to treat and it’s very quick acting so a patient can actually use this up to three times and the way we want to counsel them is first we want them

To sit down we want them to dissolve under their tongue and then they have to call 911 if their angina persists after the first five minutes so after the first dose if they don’t feel well and they’re still having chest pain they need to call 9-1-1 so that the paramedics can come assuming that the second or third dose doesn’t work because it is an emergency

Now for the chronic preventative nitrates we have isoscorbide mono nitrate brand name is emder der because of duration they last a long time the dosing is anywhere from 30 to 240 milligrams by mouth daily now it is extended release it does work for 12 hours but it also requires a 12 hour nitrate free interval if you don’t take a 12 hour break every day then

These medications stop working you build up essentially a taller and the second medication is the isosorbide dinitrate or eyesore dill and the dosing is 40 to 160 milligrams by mouth daily this is also extended release and this one also requires that 12 hour nitrate free interval now one thing from the chronic side versus the acute side these chronic medications

Have to be swallowed whole right they’re not sublingual they don’t dissolve they need to swallow it whole you can’t chew break or crush these extended release capsules and tablets all right so let’s talk about some side effects and drug interactions so the big things here is patients taking these nitrates can have headache we could see them having flushing

So redness they could become dizzy or they could have something called orthostatic hypotension which basically means low blood pressure when they get up too quickly so they get very light-headed now all of these side effects have to do with vasodilation right so as we dilate those veins we get these very distinct side effects now we do need to talk about drug

Interactions and there is one that you need to know you cannot use nitrates with pde5 inhibitors these are erectile dysfunction drugs so think of viagra the dalaphil which is cialis and essentially when both of these drugs are used at the same time it could cause severe hypotension so a dramatic drop in blood pressure and a quick overview on how it causes this

Severe hypotension remember when we take nitrates it has nitric oxide which help with the formation of cyclic gmp which then cause vasodilation now the cyclic gmp that causes the vasodilation is broken down by pde5 right so if we take a pde5 inhibitor we stop the breakdown of cyclic gmp which increases the vasodilation effect even more to the point where it could

Be potentially harmful for our patients all right so we made it to the end so let’s have a real quick summary of everything we learned so we know ischemia which means not enough oxygen for a tissue like the heart is due because of an imbalance of oxygen supply and oxygen demand this imbalance can cause something called angina pectoris which is that chest pain

So then we talked about nitrates and how they work so we know it they released nitric oxide which helped with the formation of cyclic gmp causing vasodilation which actually improved the oxygen supply to the heart and then we talked about three major drugs we talked about nitroglycerin which is our nitrostat and then our two chronic medications isosorbide mono

Nitrate and isosorbide dinitrate so these two here remember they need a 12 hour nitrate free interval to prevent that tolerance buildup and then we also had our acute angina so the nitrostat and then the chronic agents that we just talked about then we went into the side effects remember everything that had to do with vasodilation so we had headache flushing

Dizziness orthostatic hypotension and then we had our big drug interaction and remember we can’t use those nitrates with any pde5 inhibitor because of the severe hypotension so that’s everything so let’s jump into the short quiz to see what we retained question 1 which of the following is approved for acute angina question 2 nitrates increase which molecule to

Allow vasodilation question 3 nitrates are contraindicated with which of the following question 4 how long should the nitrate-free interval be for isosorbide dinitrate and thanks for watching guys i hope you learned something and a special shout out to my supporters you

Transcribed from video
How Do Nitrates Work? (Nitroglycerin) By Drug Chug