L17- Anti dysrhythmic drugs 2

Question 1

Name 2 antagonists of B adrenoceptors

Answer 1

Propranolol, atenolol

Question 2

Which Vaughan- Williams class are beta blockers in?

Answer 2

Class 2

class 2 = BETA 1 ADRENOCEPTORS.

Question 3

What are the pro-arrhythmogenic actions of the SNS activity in the heart? (that beta blockers block)

Answer 3

• Increased discharge of SAN
• Increased automaticity in atrial myocardium
• Improved conduction through AVN
• Increased automaticity in ventricular myocardium

Question 4

What do B-blockers do to heart rate?

Answer 4

• Slows down depolarisation, slower to reach threshold
• Slows sinus rythm
• Slows conduction through the AV node

Question 5

What can arrhythmias be cause by?

Answer 5

• excessive catecholamine release
• increased tissue sensitivity to catecholamines
• myocardial infarction- tissue damage- stress- overactive sinus

Question 6

Give 5 unwanted effects of beta adrenoceptor antagonists?

Answer 6

1. Bronchoconstriction- BAD FOR ASTHMA
2. Precipitation of cardiac failure/ heart block
3. Hypoglaecaemia- BAD FOR DIABETICS- covers warning signs of hypoglaecemic shock, reduce insulin secretion in type 2.
4. Cold extremities
5. Vivid dreams- propranolol because lipid soluble

Question 7

Which diseases should not be given beta blockers?

Answer 7

Asthma, diabetes, most for heart failure

Question 8

What’s th structure of Ca and Na iion channels?

Answer 8

6 TM domains in each subunit. 4 subunits.

4th TMD controls voltage stuff.

Extracellular dip between 5th and 6th.

Question 9

Where do most Na channel blockers act from?

Answer 9

Inside the cell

Question 10

What happens to the Na channels when the membrane is depolarized?

Answer 10

The voltage-sensitive part moves and the channels open, letting more sodium in. Na floods in depolarizing cell even more, more positive.

Question 11

Whats a nociceptor?

Answer 11

A bare nerve ending that sense pain

Question 12

What are the two types of pain fibres?

Answer 12

A delta fibres- fast transmission, sharp pain

C fibres- slow transmission, dull burning pain

Question 13

Which channels open and close at start and end of AP?

Answer 13

sodium open

sodium close

potassium open

potassium close

Question 14

How do local anaesthetics work?

Answer 14

They block sodium channels. so Block APs. so block nociception.

Question 15

What is the structure of local anaesthetics?

Answer 15

Aromatic group

Linker (whats broken down in body)

Amine group

Question 16

How can you determine which linker is present in a local anaesthetic?

Answer 16

If it has an i in the prefix, indicates an amide linkage.

EG lidocaine. amide linkage

Question 17

What’s the suffix for local anaesthetics?

Answer 17

caine.

eg procaine, cocaine, lidocaine

Question 18

In which conditions do local anaesthetics work best?

Answer 18

Alkaline conditions

Question 19

Why do local anaesthetics work when injected into the cell?

Answer 19

They are use-dependent blockers. so only bind to open form of the channel. Doesn;t like closed state. Likes hydrophobic pathway through channel.

Question 20

In what class of VW drugs are local anaesthetics in?

Answer 20

Class 1 drugs. Blocks sodium channels.

Question 21

What are the clinical uses of class 1 drugs?

Answer 21

Ventricular arrhythmias

Question 22

What are the potential side effects of class 1 drugs?

Answer 22

Potential problems with the CNS, as it involves lots os sodium channels. Increases risk of death after an MI.

Question 23

Which drugs are in class 1a, 1b, 1c?

Answer 23

a. disopyramide, procainamide - arrhythmias
b. lidocain - arrhythmias
c. flecainide- WPW syndrome and arrhythmias

Question 24

Which drug can treat wolff parkinson white syndrome?

Answer 24

Felcainide (class 1c)

Question 25

What are class IV drugs?

Answer 25

Calcium antagonists

Question 26

Whats an example of a class IV drug to treat dysrrhythmias?

Answer 26

Verapamil

Question 27

What do class IV drugs do in the heart?

Answer 27

Block L type VSCC

Slow SAN and AVN conduction

Suppress ectopic pacemakers

Question 28

What are the adverse effects of calcium anatgonists?

Answer 28

Dangerous in ventricular dysrrhythmias

hypotension

oedema

(something about WPW syndrome??)

Question 29

WHat are the subtypes of calcium channels?

Answer 29

L- heart

T-heart

N- neuronal

P- neuronal

Question 30

Which L type calcium blocker can’t be used to treat dyrhythmias? (exam Q likely!)

Answer 30

Nifedipine

It can trat hypertension and angine. not dyrhythmias

It’s not use dependent so blocks everything!