Inotropic Drugs

Question 1

How do Inotropic drugs function?

Answer 1

It increases the force of myocardial contraction

Question 2

What is an example of a cardiac glycoside? What 2 problems does it help with?

Answer 2

Digoxin

HF and control of the ventricular response to atrial fibrillation or flutter

Question 3

What other drugs can be used in HF?

Answer 3

Diuretics, B-adrenoceptor antagonists, RAAS drugs, vasodilators, organic nitrates

Question 4

What are the causes of HF?

Answer 4

Cardiac defect (MI, valve deficiency), CAD, hypertension, diabetes, supraventricular dysrhythmias

Question 5

What are some symptoms of HF?

Answer 5

Reflex tachycardia
Edema
Elevated venous pressure
Dyspnea
Weakness
Enlarged heart

Question 6

What are 3 drug effects on cardiac muscles?

Answer 6

Inotropic
- Pos or neg on force of muscular contractions

Chronotropic
- Pos or neg on rate of heartbeat

Dromotropic
- Pos or neg on conduction speed of electrical impulses

Question 7

What is the mechanism of action for Digoxin?

Answer 7

Increases Calcium which increases the contractility of the heart

Question 8

What are the 3 S’s of Digoxin?

Answer 8

Strengthens: positive inotropic effect (increased contractile force)

Slows: Negative chronotropic effect (reduced HR at SA node)

Slows: Negative dromotropic effect (decreases AV node conduction)

Question 9

What are 4 adverse effect of Digoxin?

Answer 9

1. It has a narrow therapeutic window, so drug levels must be monitored.
   - Low potassium levels increase toxicity
2. GI upset
   - Anorexia, nausea, vomiting, diarrhea
3. Colored vision
   - Seeing yellow, green, purple, halo vision, flickering lights
4. Cardiovascular
   - Dysrhythmias including bradycardia
   - Need to take apical pulse
   - Minimum 60 bpm

Question 10

What is used as an antidote to Digoxin?

Answer 10

Digoxin immune Fab (Digibind)

Could cause life-threatening cardiac dysrhythmias