Heart drugs

Question 1

How do Beta-blockers decrease HR?

Answer 1

Decrease If and Ica

Question 2

How do Calcium-channel blockers decrease HR?

Answer 2

Decrease Ica

Question 3

How does Ivabradine decrease HR?

Answer 3

Decrease If

Question 4

Do beta-blockers decrease contractility? If so, how?

Answer 4

Yes- decrease cAMP. This decreases Ca sensitaization of Troponin C by PKA, decreases DHPR Ca channel open and decreases Ca ATPase (on SR) activity

Question 5

Do calcium- channel blockers decreases contractility?

Answer 5

Yes- all types do

Question 6

Does ivabradine decrease contractility? If so, how?

Answer 6

No- on decreases If so only affects SAN conduction, so only affects HR not contractility

Question 7

Whats the difference between phenylakylamines and benzothiazepines, and dihydropyridines?

Answer 7

Phenylakylamines and benzothiazipines are rate slowing (alos affect contractility) CCBs and dihydropyridines are non-rate slowing CCBs (just affect SM contractility)

Question 8

What is veramapil and what does it do?

Answer 8

A phenylakylamine CCB- decreases HR

Question 9

What is dialtiazem and what does it do?

Answer 9

A benzothiazepine CCB- decreases HR

Question 10

What is amlodipine and what does it do?

Answer 10

A dyhyrdropyridine CCB- decreases contractility of vascular SM

Question 11

What effect can dihydropryridines have on HR?

Answer 11

They cause potent vasodilation which can cause reflex tachycardia via decreased firing of baroreceptors.

Question 12

What would you use a organic nitrate for and how does it work?

Answer 12

To dilate the coronary vessels (increase myocardial oxygen supply) by increasing cGMP via guanyl cyclase activation

Question 13

What would you use a potassium channel opener for and why does it work?

Answer 13

To dilate the coronary vessels (increase myocardial oxygen supply) by increasing potassium efflux, polarization of the SM cell, impairs ability to contract.

Question 14

Give two side effects of verapamil?

Answer 14

Brdycardia, constipation

Question 15

Give 3 side effects of dihydropyridines?

Answer 15

Ankle odema, headache/flushing and palpitations (reflex tachycardia)

Question 16

What is the RMP of ventricular mycoyte?

Answer 16

-65mV

Question 17

In the Vaughan Williams classification, what is class 1?

Answer 17

Sodium channel blockers (usually open to cause fast depolarisation)

Question 18

In the Vaughan Williams classification, what is class 2?

Answer 18

Beta blockers

Question 19

In the Vaughan Williams classification, what is class 3?

Answer 19

Membrane stabilisation/ blaockade of K channels (which cause slow repolorisation)

Question 20

In the Vaughan Williams classification, what is class 4?

Answer 20

CCBs- they usually cause maintain depolarisation as well as enhance contractility.

Question 21

Name 4 anti-arrythmic drugs

Answer 21

Adenosine, verapamil, amiodarone and digoxin

Question 22

What is adenosine used to treat and how does it work?

Answer 22

Arrythmia- Binds to Gs on VSM, causing relaxation and binds to Gi on SAN, decreasing HR.

Question 23

What is verapamil used to treat and how does it work?

Answer 23

Arrythmia- its a phenylakylamine CCB (so rate slowing). Used specifically to decrease ventricualr responsiveness to atrial arrythmias. Verapamil protects your Ventricular rate.

Question 24

What is amiodarone used to treat and how does it work? Name 3 side effects

Answer 24

Arrythmia- spraventricualr and ventriular tachycardias because it prevents re-entry. manily by K channel bloackade, which prolongs repolarisation. Photosensitove skin rashes, thyroid conditions and pulmonary fibrosis.

Question 25

What is digoxin used for and how does it work? Name an important consideration.

Answer 25

Arrythmia, specifically atrial fibrillation or flutter (–> decreased CO) - cardiac glycoside, central vagal stimulation increases refractory period and decrease conduction through AVN. It also inhibits the Na/K ATPase, which enhances intracllualr Ca concentration- hypokalemia increases its toxicoty