Calcium Channel Blockers Flashcards
What are calcium channel blockers?
- drugs that block Ca2+ entering a muscle cell
What are the 2 main groups of calcium channel blockers?
1 - dihydopyridines (mainly blood vessel dilation)
2 - non-dihydopyridines (mainly effects on heart)
What is the most commonly prescribed calcium channel blocker in the UK, that is a dihydopyridine?
- Amlodipine
What are 2 other drugs that are classed as non-dihydopyridines that can be prescribed as calcium channel blockers?
- Diltiazem - Verapamil
Generally out of the 2 groups of calcium channel blockers, which drugs work almost entirely on the smooth muscle and is used to treat hypertension?
- drug class = dihydopyridines
- drug name = amlodipine
Generally out of the 2 groups of calcium channel blockers, which drugs were almost entirely on the heart?
- drug class = non-dihydopyridines
- drug name = Diltiazem and Verapamil
Out of the 3 calcium channel blocker drugs that we need to know (Diltiazem, Verapamil and Amlodipine) which one is able to act on the heart and the smooth muscles?
- drug class = non-dihydopyridines
- drug name = Diltiazem
What are L-type calcium channels?
- L means long lasting
- responsible for the excitation-contraction coupling
- located in all muscle cells
- located in endocrine cells of adrenal cortex (involved in aldosterone release)
How do L-type Ca2+ channels in cardiac and smooth muscle become activated?
- cells receive action potential
- Na+ channel opens
- T-type Ca2+ channel opens
- Na+ and Ca2+ from T-type Ca2+ channels ⬆️ voltage
- L-type Ca2+ channel opens causing action potential
What is the mechanism of action of Amlodipine?
- non competitive antagonist
- binds to L-type Ca2+ channels
- ⬇️ Ca2+ in cells and inhibit vasoconstriction
What effects can Ca2+ channel blockers have on the cardiovascular system?
- ⬇️ SA node activity = ⬇️ HR
- ⬇️ cardiomyocyte Ca2+ = ⬇️ inotrope force
- ⬇️ smooth muscle Ca2+ = ⬇️ vasoconstriction
Out of the 3 calcium channel blocker drugs that we need to know (Diltiazem, Verapamil and Amlodipine) which one would be used to treat angina?
- drug class = non-dihydopyridines
- drug name = Diltiazem
Out of the 3 calcium channel blocker drugs that we need to know (Diltiazem, Verapamil and Amlodipine) which one would be used to treat arrhythmia’s?
- drug class = non-dihydopyridines
- drug name = Verapamil
In addition to treating hypertension, what other syndrome can Amlodipine be used to treat?
- Raynauds syndrome
- causes severe vasoconstriction
What is the most common side effect to Ca2+ channel blockers?
- ankle swelling
In addition to causing ankle swelling, why would Ca2+ channel blockers cause constipation?
- smooth muscle causes peristaltic contractions
- Ca2+ channel blockers inhibit GIT contractions
- stool does not move
Ca2+ channel blockers can cause postural hypotension in older patients, which in turn causes tachycardia reflex, commonly known as palpitations. What is tachycardia reflex?
- ⬇️ in BP causes ⬆️ in adrenalin
- ⬆️ in HR follows to compensate and maintain CO
How can Ca2+ channel blockers cause flushing and headaches as a side effect?
- dilating skin and brain blood vessels
What do all forms of dihydopyridines, a class of Ca2+ channel blockers end in to help remember them?
- pine
Dihydopyridines and non-dihydopyridines are both Ca2+ channel blockers, but generally work through different mechanisms. How can you remember that Dihydopyridines primarily work on dilating the blood vessels?
- Dihydopyridines start with a D
- D for Dilation of blood vessels
Dihydopyridines and non-dihydopyridines are both Ca2+ channel blockers, but generally work through different mechanisms. How can you remember that Non-Dihydopyridines primarily work on the heart?
- N D is for Non-Dihydopyridines
- N-D for Node supression in heart (small effect on blood vessels)
When looking at Ca2+ channel blockers that we need to know Diltizam, Amolodapine and Verapamil, which would you prescribe for angina?
- Diltizam
When looking at Ca2+ channel blockers that we need to know Diltizam, Amolodapine and Verapamil, which would you prescribe for arrythmias?
- verapamil
When looking at Ca2+ channel blockers that we need to know Diltizam, Amolodapine and Verapamil, which would you prescribe for high BP?
- amolodapine
