Assignment Week 2 _ NURS 6521: Advanced Pharmacology

Cardiovascular Disorders

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Cardiovascular Disorders Program Transcript

NORBERT MYSLINSKI: One of the missions of this course is to straddle the basic sciences and the clinical sciences. Many years ago, Sir William Osler said, "one cannot become a competent clinician without the full knowledge of human physiology and pathology. Without it, one flounders along in aimless fashion, never able to gain an accurate conception of disease, practicing a sort of pop- gun pharmacy, hitting now the malady and again, the patient; he, himself, not knowing which.

FEMALE SPEAKER: This week, Dr. Norbert Myslinski examines how categories of drugs, working through different mechanisms, can provide a synergistic effect, creating more treatment options.

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NORBERT MYSLINSKI: So often, in hospitals and in doctors' offices and also in medical schools and nursing schools and dental schools, there is this dichotomy between the two. I mean, you first learn the basic sciences. Then you forget about those. Then you go to the clinics. And then you learn the real stuff. But what we want to do in this course is to produce a bridge between the two and make the understanding of the clinical portions more relevant by knowing the basic science, knowing the basic science that we have.

Another way in which groups are important is synergism. In pharmacology, we have a concept where the effect of two different drugs is greater than the sum of the individual drugs, and which is very important when you combine different drugs, and especially when you have groups of drugs or categories that work via different mechanisms of action. You may have a same end result of different categories of drugs, but they work via different mechanisms. And if you do that, you're more likely to get a synergistic effect then if they all worked via the same mechanism

Some drugs work via the same mechanism no matter what their effects are, for instance, aspirin. Aspirin has many effects, right? Aspirin is an analgesic. It alleviates pain. Aspirin is anti-inflammatory. It alleviates inflammation. Aspirin is an anticoagulant for the blood. Aspirin also is antipyretic. It decreases body temperature, OK?

But how does it do it? It has many effects. By the way, all drugs have multiple effects. No drug only has one effect. All drugs have more than one effect.

But how does aspirin do all these different effects? Via the same mechanism, and that's through the inhibition of a certain compound in the body called prostaglandins. So the inhibition of the synthesis of prostaglandins produces all

Cardiovascular Disorders

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of them. There are many different types of prostaglandins, and therefore, we have different effects in there, OK?

So if we have two different drugs that work via the inhibition of prostaglandins, say, aspirin and Tylenol, they're not going to have a synergistic effect. They'll have an additive effect, right?

But if you have, for instance, a narcotic, like morphine, and then you also have Tylenol, you can have a synergistic effect with those two. Although, with Tylenol and aspirin, there is a ceiling. You can take two or three tablets and that's the maximum pain relief you're going to get, no matter if you take five or 10 after that. You may have gastric distress, but you won't have more of an effect. There's a ceiling.

With morphine, though, there is no ceiling. You just keep going and going and going. You get more and more pain relief until your respiration shuts down, and you die.

So if we look at hypertension, that silent killer, that's one disorder that we have a wealth of groups and categories of drugs working via many different mechanisms. So we can have a very nice synergistic effect. We can tailor make their pharmacotherapy, so they can control their blood pressure with the least amount of side effects. And they can function in society.

For example, you have your ACE inhibitors. You have your angiotensin inhibitors. You have your beta blockers. You have your calcium channel blockers. You have your diuretics. All of them can reduce blood pressure. All of them work via different mechanisms.

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There are two types of blood vessels that go up. It's the carotids and the vertebrals. And then they go into a little area here and are distributed throughout the brain.

And one of the most common causes of disability that we have is stroke. Now, stroke is when you have a deprivation of oxygen going to a part of the brain. And that's usually due to one of three things. Either there's a buildup of a clot in that blood vessel, a primary site. So the blood stops going to that area.

Or you have a clot that breaks off from a different part of your body, more likely from the left side of the heart, because you may have atherosclerosis, buildup of fatty tissues and clots there. And if one breaks off, it can go into your brain and to clog a blood vessel. It can happen very quick.

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Or you can have a weak blood vessel wall, so that it blows up like a balloon. That balloon is an aneurysm, and eventually, it busts. When it bursts, then you have a stroke in that part of the area of the brain.

Now, the symptoms of a stroke in many patients that nurses treat for chronic time periods-- the symptoms of a stroke can be quite varied, as many functions that are functions of the brain, depending upon where the stroke is-- depending upon where the stroke is, OK? For instance, if it happens here in the back of the brain, you'll have a lot of visual symptoms, because this is where the brain processes visual information, occipital lobes.

If you have one over here, in the temporal lobes, that processes hearing, OK? So you'd have hearing problems, OK? If you have a stroke that affects this part over here, this is somatosensory cortex. You may have a problem with the feeling, touch, and pressure in different parts your body. Over here is the motor cortex, and that has to do with movement. So you may have problems with movement of your body, OK?

So it all depends upon where that injury is. And it's very interesting, because when there is a stroke, the main part dies. And then the other parts around it shut down. And unless treatment is given quickly and drugs can be given that can dissolve a clot real quickly, the parts that sort of are not dead yet, but they're affected around there, if you're not treated quickly, then that part may also die.

So when you first have a stroke, your symptoms involve not only the dead part but also the part back here that's sort of shut down, right? If you're treated quickly-- if you have the signs of a stroke, you have what we call a brain attack, and you get right there to the emergency center, you can dissolve the clot.

And then you can have a reversal of some of the symptoms. Like this function of all these ones around the dysfunctional ones can come back, and we can have reversal of the symptoms. But if you don't get to treatment, these will eventually die too, and those symptoms will stay around for a very long time. And so it all depends upon where the dysfunction is and that determines what kind of symptoms we have.

Cardiovascular Disorders Content Attribution

Painting of Sir William Osler courtesy of Alan Mason Chesney Medical Archives Johns Hopkins Medical Institutions