CCB Flashcards
What are THREE common indications?
Hypertension
Angina in ppl w/ IHD
Non-dihydropyridine- control heart rate in people with SVT arrhythmias including SVT tachycardia, AF atrial flutter.
What is the mechanism of action of CCB
Calcium channel blockers decrease calcium ion (Ca2+) entry into vascular and cardiac cells, reducing intracellular calcium concentration.
This causes relaxation and vasodilation in arterial smooth muscle, lowering arterial pressure.
In the heart, they reduce myocardial contractility.
They suppress cardiac conduction, particularly across the atrioventricular (AV) node, slowing ventricular rate.
Reduced ventricular rate, contractility, and afterload, reduce myocardial oxygen demand, preventing angina.
What are the two types of CCB and how do they differ?
Dihydropyridines,
amlodipine and nifedipine, are relatively selective for the vasculature.
Non-dihydropyridines;
more selective for the heart. verapamil is the most cardioselective, whereas diltiazem also has some effects on blood vessels
What are common side effects of dihydropridine CCB?
ankle swelling, flushing, headache and palpitations caused by vasodilation and compensatory tachycardia.
What are common side effects of non-dihydropyridine?
-Commonly constipation
- less common: bradycardia, heart block and cardiac failure
-As diltiazem has mixed vascular and cardiac actions, it can cause any of these adverse effects including dihydropyridine ones.
Who should be prescribed with caution/avoided?
Caution:
impaired left ventricular function as they can precipitate or worsen heart failure.
Avoided:
AV nodal conduction delay as they may provoke complete heart block.
When should amlodipine and nifedipine be avoided in patients?
Unstable angina- as vasodilation causes a reflex increase in contractility and tachycardia, which increases myocardial oxygen demand.
Severe aortic stenosis:
can cause cardiac collapse
What are common interactions with non-dihydropyiridne CCB?
Beta blockers.
Both drug classes are negatively inotropic and chronotropic, and may cause HF, bradycardia and asystole.
Avoid grapefruit juice
What are dosages and methods of administration for dihydropuyiridne CCB?
Amlodipine:
half life 35-50hours
5-10mg OD
Nifedipine MR:
min 10mg max 90mg (based on brand) for hypertension and angina
What are dosages and methods of administration for non-dihydropyiridne CCB?
Verapamil- IV acute arrhythmias
Initially 5–10 mg, followed by 5 mg after 5–10 minutes if required, to be given over 2 minutes, preferably with ECG monitoring.
Angina:
240mg BD
SVT:
40-120mg TDS
Diltiazem MR:
Angina
90mg orally 12hrly
What are half lives of some CCB and why is it significant
Nifedipine:2-3 hours
Verapamil: 2-8 hours
dilitazem: 6-8 hours
Affects frequency of administration.
Why must MR diltiazem and nifedipine be prescribed by brand?
As they may not be bioequivalent.
What are monitoring requirements for hypertension?
BP
Start with low dose and titrate upwards increasing if necessary at 4 week intervals
Measure BP 4 weeks post dose change
What are monitoring requirements for arrhythmias?
rhythm from ECG
Pulse rate
