Antianginal Theraby - 38

Question 1

factors that contribute to O2 demand

Answer 1

preload, afterload, HR, and

cardiac contractility

Question 2

The major agents used to alter these parameters

Answer 2

nitrates, β-blockers, and calcium channel blockers.

Question 3

1- Nitrates

Answer 3

-As Nitroglycerin, Isosorbide Dinitrate, Isosorbide Mononitrate (oral F is
100 %)

Question 4

Mechanism of action of nitrates

Answer 4

Vasodilatation via release of nitric oxide; major effect is preload
reduction (veins dilate, blood pools in veins, and venous return to the
heart decreases), resulting in decreased O2 demand.

Question 5

Uses of Nitrates

Answer 5

1-Angina pectoris
-Stable angina, unstable angina, and variant angina.
-Sublingual nitroglycerin is the drug of choice to control acute attack of
angina
2-CHF as it decreases preload, combined with hydralazine
3-I.V. nitroglycerin is used in hypertensive emergency in ischemic
patients
4-Diffuse oesophageal spasm

Question 6

Side effects of nitrates

Answer 6

Side effects

• Reflex tachycardia, orthostatic hypotension
• Excessive vasodilation as headache (considered as beneficial side
  effect) , flushing, dizziness, nausea and vomiting.
• Tolerance
• Drug interaction with sildenafil

Question 7

β-blockers

Answer 7

-As Metoprolol, Atenolol, Propranolol

Question 8

Mechanism of antianginal effect of Beta blockers

Answer 8

Reduce O2 demand by reducing HR and cardiac contractility.
Decrease BP, so can decrease afterload
Can use any drug except drugs with partial agonist activity as -
pindolol and acebutolol

Question 9

Uses of beta blockers

Answer 9

1-Stable angina, not variant (Prinzmetal) angina (because β-blockade can
disrupt the balance of α and β effects and worsen vasospasms).
2-Headache prophylaxis
3-Essential tremor.
4-Other uses……see ANS

Question 10

Side effects of beta blockers

Answer 10

• Bradycardia, AV block.
• Contraindicated in asthma and COPD patients (only beta-blockers
  selective for β1-receptors, such as atenolol and metoprolol, can be used)

Question 11

3- Calcium Channel Blockers

Answer 11

Dihydropyridines as Nifedipine, Amlodipine and any……dipine

- Non-dihydropyridines as Verapamil, Diltiazem

Question 12

Mechanism of action of Calcium Channel Blockers

Answer 12

-Block L-type Ca2+ channels, inhibiting entry of Ca2+ into arteriolar
smooth muscle; this action results in arteriole dilation and reduced SVR.
- Also inhibit entry of Ca2+ into heart leading to decrease all properties
of the heart as decrease heart rate, conduction of A-V node and
contraction

Question 13

Site of action of Calcium Channel Blockers

Answer 13

Vasoselective agents work predominantly at the arteriolar smooth
muscle. The most commonly used class is the dihydropyridines
(including nifedipine and amlodipine).
■ Nonselective agents act equally on the heart and the arterioles. Their
vasodilating action is not as potent as that of the dihydropyridines, but
they also reduce cardiac contractility. Examples are verapamil and
diltiazem.

Question 14

Mechanism of antianginal effect of Calcium Channel Blockers

Answer 14

1-Decrease O2 demand:
■ Verapamil, diltiazem: Decrease HR and contractility (like β-blockers)
and reduction of the afterload.
■ Nifedipine: Decreases afterload via vasodilation.
2-Increase coronary supply

Question 15

Uses of Calcium Channel Blockers

Answer 15

1- Stable angina and variant (Prinzmetal) angina (calcium channel
blockers are the drugs of choice).
- Nifedipine is recommended to be combined with beta-blockers while
verapamil and diltiazem are contraindicated to be combined with betablockers.
2-Mild to moderate hypertension.
3-Raynaud phenomenon
4- Supraventricular arrhythmias as atrial tachycardia, flutter and
fibrillation (correct only tachycardia but in flutter and fibrillation used to
protect ventricle by decreasing A-V nodal conduction
5-Prophylaxis of migraine (verapamil)
6-Nimodipine used to treat cerebral vasospasm
7-Inhibit premature delivery (Nifedipine)

Question 16

Side effects Calcium Channel Blockers

Answer 16

1- Nifedipine may cause reflex tachycardia and manifestations of
excessive vasodilation as headache, nausea, dizziness and flushing
2-Peripheral edema (especially dihydropyridines)
3- Constipation due to relaxation of GIT smooth muscles
4- Verapamil and diltiazem can cause bradycardia, and AV block.
5-Verapamil has negative inotropic effects and can cause signs of heart
failure.
6-Verapamil and diltiazem not used with beta blockers to avoid excessive
depression of the hear