Angina 2: Calcium channel blockers

Question 1

Enumerate dihydropyridine CCBs

Answer 1

• Long acting: amlodipine
• intermediate acting: Nifedipine, (nitrendipine, felodipine, Isradipine)
• Short acting: Nicardipine, Nimodipine

-dipine

Question 1

the 2 groups of CCB

Answer 1

DHP & Non DHP:
* Dihydropyridines
* non Dihydropyridines

Question 2

Enumerate Non-Dihydropyridine CCBs

Answer 2

• Verapamil & Diltiazem

Question 3

which CCB has the highest Oral availability

Answer 3

dihydropyridine = Nefedipine

Question 4

which CCB has the highest first pass metabolism percentage

Answer 4

Non-dihydropyridine = Verapamil

Question 5

Dihydropyridines mainly cause ____

Answer 5

Vasodilatation

Question 6

Non-dihydropyridines mainly cause ___

Answer 6

inhibition of the heart

Question 7

mechanism of action of CCBs

Answer 7

• block voltage gated L-type calcium channels, causing decreases influx in Ca+, leading to:

Cardiac inhibition, Arteriolar VD & smooth muscle relaxation

Question 8

Pharmacological action of Non-dihydropyridines (verapamil & diltiazem)

Answer 8

Powerful Cardiac depressent:
* -ve Chronotropic by inhibiting SAN (antagonzing relfex tachycardia done by Nitrates)
* -ve inotropic (decrease work & contractility)
* -ve dromotropic (decrease AV conduction
* Decrease automaticity (deceases ectopic focus formation –> Class IV antiarrhythmic
* less peripheral VD & hypotension than Nifedipine
* Potent Cornary VD

Question 9

contraindication of the negative dromotropic effect of Vermapamil/ diltiazem

Answer 9

• Heart block
• beta blockers or digitalis

Question 10

Pharmacological actions of Nifedipine

Answer 10

Poweful VD:
* potent Arterial VD ➡️ decrease Peripheral resistance & afterload
* Weak venous VD ➡️ Decrease Vr & preload
* Coronary VD: coronary steal phenomenon may occur (VD of small coronaries of non ischemic area stealing blood going to ischemic areas
* Hypotension (causes reflex tachycardia)

Question 11

explaine why Nifedipine is allowed in heart failure

Answer 11

has weak myocardial depressing effect, especially minmial negative inotropic effect: so CO can be maintained or even increased

Question 12

enumerate and describe theraputic uses of CCB

Answer 12

• Prophylaxis of all types of Angina
• Cardiac arrhythmias (especially Verapamil)
• Hypertrophic Obstructive cardiomyopathy
• premature labour
• reduce severity of raynaud’s episode
• Cerebral spasm caused by subarachnoid hemorrhage (especially nimodipine)
• Migrane prophylaxis (nimodipine & Flunarizine)

Question 13

Explain why skeletal muscles aren’t depressed by CCBs

Answer 13

due to presence of intracellular pools of Calcium ions

Question 14

Adverse effects of CCBs

Answer 14

• Headache
• Flushing
• Constipation (especially Verapamil)
• Ankle edema (especially Nifedipine)
• Hypotension
• Heart failure
• Heart block
• Bradycardia

Question 15

Drug interactions of CCBs

Answer 15

• Verpamil: decreases Digoxin renal excretion –> aggregate heaet block
• Verpamil + beta blockers: severe cardiac depression
• Nifedipine + nitrates: severe hypotension & reflex tachycardia

Question 16

other CCBs and their usage

Answer 16

Flunarizine:
* Prophylaxis of migrane
* Peripheral vascular disease

Indapamide:
* thiazide diuretics