Cardiac drugs

Question 1

digoxin

Answer 1

use: HF, atrial fibrillation
mechanism: inhibits na+/K+ATPase -> increases intracellular Ca2+
effect: positive inotrope (force) , negative chronotrope (speed) and dromotrope (conduction)

Question 2

Dobutamine

Answer 2

use: acute treatment of severe HF
mechanism: beta 1 agonist (selective for heart)
effect: positive inotrope (force)

Question 3

Pimobendan

Answer 3

Use: HF

mechanism: phosphodiesterase inhibitor (PDE3 and PDE5) in heart and blood vessels (Increases cAMP-> inc. heart contractility and decreases smooth muscle contraction = vasodilation, and bronchodilation)
effect: positive inotrope, vasodilator

Question 4

metoprolol

Answer 4

use: HCM
mechanism: selective beta-blocker -> slows HR, relaxes ventricular wall = improved diastolic filling
effect: decreases HR but improves cardiac filling

Question 5

enalapril/benazepril/imipril

Answer 5

use: HF + hypertension
mechanism: inhibits angiotensin-converting enzyme (ACE inhibitor)
effect: reduces Ang II levels -> vasodilation (mainly arterioles), reduces aldosterone release

Question 6

valsartan/telmisartan

Answer 6

use: AT1 receptor antagonist
mechanism: inhibits the action of Ang II
effect: vasodilation (mainly arterioles), reduces aldosterone release

Question 7

nitroglycerin, nitroprusside

Answer 7

use: HF
mechanism: exogenous sources of NO
effect: venodilation and reduced preload

Question 8

prazosin

Answer 8

use: HF, hypertension
mechanism: alpha 1 - adrenergic receptor antagonist
effect: arteriolar dilation and reduced afterload

Question 9

hydralazine

Answer 9

use: HF, hypertension
mechanism: decrease vascular smooth muscle calcium
effect: arteriolar and venous dilation (reduce preload and afterload)

Question 10

sildenafil

Answer 10

use: pulmonary hypertension
mechanism: phosphodiesterase inhibitor (PD5) - preventing cGMP breakdown
effect: vasodilation in lung and penile circulation, reduced pulmonary pressure

Question 11

Class 1 antiarrhythmics

Answer 11

drugs: quinidine, procainamide, lidocaine
use: mainly ventricular arrhythmias, particularly tachycardias
mechanism: Na” channel inhibitor
effect: decrease Na+ current -> prolonged QRS phase -> reduce HR and cardiomyocyte excitability

Question 12

Class 2 antiarrhythmics

Answer 12

drugs: metoprolol, atenolol
use: SVT especially when excessive sympathetic stim is the cause
mechanism: beta 1 adrenergic receptor antagonists
effect: decreased chronotrope, dromotrope, and inotrope (dec. HR, contractility, force)

Question 13

Class 3 antiarrhythmics

Answer 13

drugs: amiodarone, bretylium, sotalol
use: refractory V tach especially those arising from reentry
mechanism: K+ channel inhibitor
effect: decrease K+ current -> prolonged repolarization phase -> reduced HR

Question 14

Class 4 antiarrhythmics

Answer 14

drugs: verapamil, diltiazem
use: SVT, HCM
mechanism: Ca2+ channel inhibitor
effect: decreases Ca2+ current -> slows spontaneous depolarization in pacemaker cells -> negative chronotrope (slower HR)