What are the mechanisms that underlie the drugs that are used to treat hypertension? Drugs like ACE inhibitors, diuretics and beta blockers? That’s what we cover in this video.
Transcript of Today’s Episode
I want to talk about treatment of hypertension. Here is the problem with hypertension. Hypertension is often undiagnosed because of the fact that the symptoms are very vague, things like fatigue, light-headedness, and headaches and those types of things are what you usually have and it’s not really giving you any significant symptoms until you have serious problems.
Now, when it comes to treatment, there are a number of things that can be done and of course, the first thing that we can look at is some lifestyle modifications and how that affects general cardiovascular health. So, we’re dealing with things like:
- stopping smoking
- weight reduction or weight loss
- regular aerobic exercise
- reduction in caffeine / coffee intake
- reduction in sodium / salt intake
- eating well
Eating fruits and veggies. Of course, it’s not just fruits and veggies but, that’s a good staple in terms of thinking about health.
Some of these general things that we can do are going to help with preventing, help with reversing the effects of hypertension.
Now, of course, in some cases, it’s going to be a little more advanced than these lifestyle modifications. Yes, you want to make them but, in some cases, you’re going to need some extra help.
We’re going to talk about some of the drugs that can be taken to really help with hypertension. So, let’s take some examples.
We spoke about this in a previous video where we showed that blood pressure is equal to cardiac output times peripheral resistance. If you increase any of these, you’re going to increase the blood pressure.
Now, on the flip side, if one of these are increased and that’s causing an increase in blood pressure, what you want to do is reduce one or both of these values so that, that can reduce the blood pressure and stop it from getting any worse. There are a number of ways to do this using pharmacological agents.
First, I want to talk about those that are going to decrease peripheral resistance, or at least stop that from increasing.
Drugs Affecting Peripheral Resistance
The first one will be what we call, ACE inhibitors. As you can imagine, that’s going to inhibit this enzyme here, essentially knocking that out so that we’re not getting the conversion of angiotensin I to angiotensin II which is such a potent vasoconstrictor that is going to increase peripheral resistance significantly.
So, we’re stopping this process from happening so that peripheral resistance can be decreased or at least, not increased anymore. That is the result of using the class of drugs that we call, ACE inhibitors.
There’s another class of drugs that’s going to also work against this increase in peripheral resistance and those are drugs that are going to block, so let’s just say “block” sympathetic stimulation. If you’re blocking sympathetic stimulation, sympathetic stimulation normally causes vasoconstriction.
So, you’re going to stop this right here so that, you are reducing the amount of vasoconstriction and in essence, you’re decreasing peripheral resistance. So, those are two different types of drugs that are going to work to reduce peripheral resistance. And, if we reduce peripheral resistance, we reduce blood pressure and we are helping to stop this cycle from continuing. Those are drugs that are going to affect peripheral resistance.
Drugs Affecting Cardiac Output
Let’s talk about some drugs that are going to affect cardiac output.
Number one, those are going to be your diuretics. What is that going to cause? Diuretics is causing an increase in urination. If you cause an increase in urination, what you’re basically doing is counteracting this process where we’re going to have an increase in water reabsorption.
Instead of having an increase in water reabsorption, we’re going to have an increase in water secretion. So, water won’t be going back to the blood stream. Along with sodium, it’s going to be leaving. So, we’re going to cause sodium ions to leave, and as a result of that water is also leaving.
Those are your diuretics. And of course, if that is happening, that is going to cause a reduction in blood volume, and as a result of that, a reduction in cardiac output and a reduction in blood pressure. So, we’re stopping the process in terms of decreasing the cardiac output.
Another way of affecting cardiac output more directly is with a class of drugs that are called beta-blockers. Beta blockers are going to block the beta receptors on the heart and those are responsible for responding to sympathetic stimulation. Sympathetic stimulation, that’s fight or flight. It’s speeding things up. It’s causing increased contraction of the heart.
If you’re blocking those beta receptors, we are basically going to be decreasing the cardiac output because the heart will not contract as strongly. As a result of that, we’re decreasing the cardiac output, decreasing the blood pressure, so we’re stopping the process right here, or counteracting the process right here.
So, those are some of the drugs that are used, some of the main types of drugs. We have our ACE inhibitors and we have drugs that block sympathetic stimulation basically in essence either knocking out or reducing the effect of that angiotensin converting enzyme and reducing the amount of vasoconstriction and then, we have those that are going to affect cardiac output, either by causing more water excretion or the beta blockers that are going to reduce the amount of the strength of contraction of the heart.
So, there you have it. That’s it for this video. I’ll see you in the next one.