Cardiac Glycosides

Question 1

Which class of CHF is the following: fatigue, shortness of breath, and coughing on exercise?

Answer 1

Class II

Question 2

Which class of CHF is the following: comfortable at rest, but exercise minimal?

Answer 2

Class III

Question 3

Which class of CHF is the following: strenuous exercise limited?

Answer 3

Class I

Question 4

Which class of CHF is the following: no capacity for exercise, clinical signs at rest?

Answer 4

Class IV

Question 5

Which drug comes from the following plants: Digitalis lanata & Digitalis purpurea?

Answer 5

Digoxin

Question 6

What are the 3 components of a cardiac glycoside?

Answer 6

1. Lactone
2. Steroid
3. Sugar

Question 7

Digitoxin and Digoxin differ based on their “Y” component. What is the “Y” component of Digoxin?

Answer 7

OH

Question 8

Digitoxin and Digoxin differ based on their “Y” component. What is the “Y” component of Digitoxin?

Answer 8

H

Question 9

Which of the following has the longer half-life: Digoxin or Digitoxin?

Answer 9

Digitoxin (there is a “t” for “time”)

Question 10

What 4 conditions can Cardoxin LS be used to treat?

Answer 10

1. Heart failure
2. Atrial flutter
3. Supraventricular fibrillation
4. Atrial fibrillation

Question 11

What are the 3 major effects of cardiac glycosides?

Answer 11

1. Positive ionotropic effect
2. Negative chronotropic effect
3. Negative dromotropic effect

Question 12

What type of effect is the slowing of the heart rate?

Answer 12

Negative chronotropic effect

Question 13

What type of effect is the slowing of conduction at the AV node?

Answer 13

Negative dromotropic effect

Question 14

What type of effect is the increased force and velocity of contraction of the heart?

Answer 14

Positive ionotropic effect

Question 15

What is the half-life of Digoxin in the dog?

Answer 15

23-39 hours

Question 16

What is the half-life of Digoxin in the cat?

Answer 16

25-78 hours

Question 17

What is the half-life of Digoxin in the horse?

Answer 17

13-23 hours

Question 18

What is the primary mode of elimination of Digoxin?

Answer 18

Renal

Question 19

What are the deleterious effects of Digoxin on the rhythm of the heart?

Answer 19

1. AV block
2. Ventricular fibrillation
3. Tachycardia
4. Atrial arrhythmia
5. Ventricular arrhythmia

Question 20

What are the symptoms of DIgoxin toxicity?

Answer 20

1. Extrasystole
2. Coupled beats
3. GI disturbances (anorexia, vomiting, diarrhea)

Question 21

Pimobendan is an Inodilator. What is the common name for Pimobendan in veterinary medicine?

Answer 21

Vetmedin

Question 22

What are the 2 mechanisms of action of Inodilators?

Answer 22

1. Calcium sensitization

2. Inhibition of phosphodiesterase III

Question 23

For Inodilators, how does the calcium sensitizer work?

Answer 23

Tropin I inhibits actin and myosin interaction until calcium binds to Troponin C. Calcium sensitizer increases calcium binding to Troponin C.

Question 24

For Inodilators, how does the Phosphodiesterase III inhibitor work?

Answer 24

Phosphodiesterase III inhibitor prevents cAMP breakdown and increases PKA (protein kinase A) action, increasing voltage-activated calcium currents.

Question 25

What are the 5 therapeutic effects of Cardiac Glycosides and Pimobendan?

Answer 25

1. Increased cardiac output 2. Decreased venous pressure 3. Decreased heart rate 4. Reduced heart size 5. Water loss = reduced body weight

Question 26

Name 3 other positive ionotropic drugs.

Answer 26

1. Dobutamine 2. Dopamine 3. Amrinone

Question 27

Dopamine interacts with which receptors on the heart?

Answer 27

D5

Question 28

Dobutamine is a ____ agonist.

Answer 28

Beta-1

Question 29

Amrinone is a _____ inhibitor.

Answer 29

Phosphodiesterase III