B - 15. Drugs used for treatment of heart failure II: Positive inotropic agents. Pharmacotherapy of acute heart failure.

Question 1

Main action

Answer 1

Stronger contraction of heart -> stroke volume increases -> increased CO

Question 2

Cardiac glycosides names

Answer 2

digoxin (kidney excretion)

digitoxin (liver excretion)

Question 3

Cardiac glycosides action on myocytes

Answer 3

Inhibits Na+/K+ pump on cardiac myocytes -> forces Na+ to use Na+/Ca++ exchange -> Ca++ increased -> increased contractility

Question 4

Cardiac glycosides action vagus nerve

Answer 4

Inhibits Na+/K+ pump -> inhibiting parasympathetic innervation of atria

Question 5

Problems with cardiac glycosides

Answer 5

• does not reduce mortality
• A lot of side effects
• Narrow therapautic window; easy to OD

Question 6

Cardiac glycoside SE

Answer 6

• GI problems
• anorexia
• ECG: T-wave changes, short QT, ST-depression, arrythmias
• Hyperkalemia
• Neuro: confusion, disorientation, xanthopsia

Question 7

Phosphodiesterase inhibitor names

Answer 7

Milrinone

Question 8

Phosphodiesterase inhibitor action

Answer 8

PDE inhibition -> cAMP increase -> Ca++ increase

• contractility of myocytes increase
• vasodialation of vessels

Question 9

Phosphodiesterase inhibitor problems and SE

Answer 9

• increases mortality in chronic HF

SE
- arrythmias, hypotension

Question 10

B-1 agonist name

Answer 10

Dobutamine

Question 11

B-1 agonist function

Answer 11

B1 agonistic, partially B2 (vasodialation - lowers TPR)
->HR and contractility increase, but also oxygen and energy demand of heart

Used for acute HF and cardiogenic shock (<60 mmHg sys)

Question 12

B-1 agonist problems and SE

Answer 12

Can’t use chronically; tolerance develops

SE
Tachycardia, palpatations, arrythmias

Question 13

Other drugs

Answer 13

Levosimendan

Increases cardiac sensitivity to Ca++