Dihydropyridine calcium channel blockers are a class of drug that cause arterial vasodilation, used to lower blood pressure in order to treat hypertension and angina. In this video, I'll teach you my visual mnemonic to remember the names, mechanism, clinical uses, and side effects of the DHP calcium channel blockers so you'll be ready come test day. Ooh, an ice cream stand.
That sounds refreshing on a hot day like today. But this isn't just any ice cream stand. It's a Dippin'Dots stand.
Notice the DHP in the Dippin'Dots sign? The DHP in Dippin'Dots can help you remember that we are talking about DHP calcium channel blockers. And not only that, all DHP calcium channel blockers have the ending dip-een.
Get it? Because Dippin'Dots kind of sounds like dip-een. You can even remember dipine dots.
On test day, you might see drug names like amlodipine, nifedipine, and felodipine. But since they all end in dipine, you'll know right off the bat that they are DHP calcium channel blockers. Now, you might have heard elsewhere that calcium channel blockers end in peen, but actually there are several other medications that end in peen and aren't calcium channel blockers. Take atropine, for example. That's why these dip-in dots will help you remember to look for the full ending, dip-ine.
Let's get some dip-in dots, shall we? Looks like we'll have to get the worker to help us. There's no way we're getting past that big lock without a key.
By the way, this lock on the ice cream freezer can help you remember that we were talking about calcium channel blockers. Because ice cream has a lot of calcium, right? The lock is blocking the ice cream, just like this medication blocks the calcium channels. Maybe we should ask that jogger if she needs help. It looks like she's tripped and is falling right into this Dippin'Dots stand.
And grabbing onto that umbrella doesn't seem to be doing her any good. Notice how the hole in the fabric there is widening and getting bigger as she falls. That reminds me how calcium channel blockers cause arterial vasodilation.
You know. a widening hole for vessel dilation? You see, calcium normally enters the walls of blood vessels via the calcium channels in order to cause the vessels to constrict.
So, when the calcium channels are blocked, say by amlodipine, the vessels instead dilate. This works to decrease the blood pressure by way of reducing vascular resistance. To understand why vasodilation decreases blood pressure, think about the analogy of a garden hose. Letting go or dilating a squeeze on the hose reduces the resistance to flow, causing the water, or blood, inside to spurt out with less pressure, right?
This ice cream freezer isn't doing a very good job at keeping the Dippin'Dots cold. And because of its deflated tire, the worker can't move it out of the hot sun into the shade. Just like this tire pressure is decreasing as the tire deflates, calcium channel blockers are used to decrease blood pressure. Got that? A deflating tire for a decrease in blood pressure.
Calcium channel blockers are used to lower high blood pressure. In other words, they treat hypertension. They do this through the mechanism we just talked about, atrial vasodilation. In addition to lowering blood pressure, there's another clinical indication for calcium channel blockers. So let's move on.
Yeah, the longer I'm watching, the more I think this jogger needs a hand. She looks like she's in pain. Especially with the way she has hit her chest on the ice cream freezer like that.
Ouch. By the way, another common clinical use for DHP calcium channel blockers is angina or chest pain. This jogger getting hit in the chest is our symbol for angina, because you bet her chest is in pain right now.
Angina is usually caused by insufficient blood flow to the heart to meet its demands. One of the ways we can remedy this is to decrease the work of the heart. by reducing the resistance, or pressure, that it has to pump against. And what do the DHP calcium channel blockers do?
Oh yeah, they conveniently decrease blood pressure, which obviously reduces the work and oxygen demand of the heart, thereby treating angina. Got that? Let's move on. Oh, now I see why the jogger is falling.
It's that broken Dippin'Dots freezer's fault. Since the worker can't move the freezer out of the sun due to the flat tire, The ice cream inside the freezer is melting and leaking out of the bottom, which caused the jogger to slip. This leaking, pooling liquid kind of reminds me of edema, because edema is essentially fluid leaking out of vessels and pooling into the interstitial space. You can use this leaking ice cream to remember that one of the biggest side effects with DHP calcium channel blockers is peripheral edema, which basically manifests as swelling in the hands and feet. The finding of edema should make sense actually because peripheral edema is often a downstream effect of vasodilation.
In fact, all the side effects we're going to talk about today are directly related to the vasodilatory effects of calcium channel blockers. This jogger must have been running pretty fast. That's probably why she didn't see that puddle of melted ice cream. I can tell she was hustling because of her red face. Flushing is actually another side effect.
of DHP calcium channel blockers. Flushing is the result of increased blood flow to the superficial skin and face due to vasodilation, which, as we covered, is the main mechanism of these drugs. Again, use this runner's red face to help you remember the side effect of flushing.
Now, take a look at the jogger's fitness watch. These watches are really handy for exercising because they can tell you what your heart rate is. And it looks like this runner's heart rate is really high, which is what you'd expect from someone running, right? This fast heart rate on that watch is our symbol for tachycardia.
Calcium channel blockers can cause reflex tachycardia, which is the body's way of responding to or compensating for a sudden drop in blood pressure. The heart is beating faster in attempt to pump more blood out to restore blood pressure. I wonder why this Dippin'Dots worker didn't step in to help this poor jogger.
Wait a second. I know that look on his face. He has a brain freeze. In fact, headache is the final side effect we want you to remember for the DHP calcium channel blockers. Brain freeze for headache.
Easy, right? Calcium channel blocking drugs like amlodipine can cause headaches due to an unclear mechanism. The final thing you need to notice is this sign taped to the ice cream freezer. Aw, man. Looks like they're all out of the grapefruit flavored Dippin'Dots.
It's no wonder. Now that we've seen how fast the Dippin'Dots worker has been eating them, in fact, I think he is eating the last of the Grapefruit Dippin'Dots just now. Just like how this ice cream stand is out of Grapefruit-flavored Dippin'Dots, patients who are taking calcium channel blockers should stay away from Grapefruit juice.
Grapefruit juice prevents the body, and more specifically, the liver, from breaking down the drug, meaning that the drug levels in the body increases to potentially cause severe hypotension. If you see a question on the NCLEX about DHP calcium channel blockers and diet, remember that your patient should stay away from grapefruit juice. That's it for the DHP calcium channel blockers. Let's do a quick recap before we wrap up.
DHP calcium channel blockers consist of medications that end in dipine, including amlodipine, nifedipine, and felodipine. These drugs work. by causing arterial vasodilation, which has the overall effect of reducing blood pressure.
Clinically, these drugs are used to treat hypertension and angina. Side effects include peripheral edema, flushing, reflex tachycardia, and headache. Last but not least, patients taking calcium channel blockers should avoid grapefruit juice. Thanks for joining us. Now let's get some Dippin'Dots for ourselves to celebrate learning all about the DHP calcium channel blockers.
I'll see you in the next one.