Lecture 11: Clinical Pharmacology

Question 1

What are three effects of VW class I drugs?

Answer 1

Slow rate of depolarisation, slow conduction velocity, slow rate and force of contraction (during refractory period)

Question 2

How do class 1a act?

Answer 2

Block fast Na to prolong refractory period

Question 3

How do class 1b act?

Answer 3

Block refractory Na channels to prevent premature depolarisation

Question 4

How do class 1c act?

Answer 4

Inhibit fast Na, prolong QRS, don’t affect refractory period, decrease automaticity

Question 5

What class of drug is quinidine?

Answer 5

1a

Question 6

What is quinidine used for?

Answer 6

To convert AF in horses

Question 7

What are some side effects of quinidine?

Answer 7

GI toxicity, hypotension, decreased contractility, vasodilation, enhanced AV conduction, AV block

Question 8

What class of drug is procainamide?

Answer 8

1a

Question 9

What class of drug is lidocaine?

Answer 9

1b

Question 10

When is lidocaine used?

Answer 10

Ventricular arrhythmia with haemodynamic effects on the dog

Question 11

How do you give lidocaine?

Answer 11

IV bolus first with ECG to test effect

Question 12

What are side effects of lidocaine?

Answer 12

Nausea, vomiting, tremors, convulsions

Question 13

What conditions can lidocaine potentiate?

Answer 13

Automaticity deficiencies, cardiac standstill

Question 14

Which drugs can lidocaine interact with?

Answer 14

Clearance reduced by propranolol, anaesthetics, chloramphenicol etc

Question 15

What class are tocainide and mexilitine?

Answer 15

1b

Question 16

What are the class 2 drugs?

Answer 16

beta blockers

Question 17

Are beta blockers -ve chronotropes or -ve inotropes?

Answer 17

Both

Question 18

How often do you give propranolol per day?

Answer 18

3x so reduced compliance compared to atenolol

Question 19

Why don’t you give beta beta blockers in CHF?

Answer 19

Reduces CO

Question 20

In what conditions do you give beta blockers?

Answer 20

Unstable myocardium (ventricular arrhythmias)

Question 21

How do class III drugs work?

Answer 21

Prolong action potential and refractory period, block inward channels, don’t compete for beta receptors

Question 22

What is amiodarone used for?

Answer 22

Supraventricular arrhythmias in dogs

Question 23

How does sotolol work?

Answer 23

Class III and beta blocker

Question 24

What are side effects of sotolol?

Answer 24

Few negative effects, other than in CHF

Question 25

What is sotolol used for?

Answer 25

Boxers with DCM or CM, or other ventricular arrhythmias

Question 26

How do class IV drugs work?

Answer 26

Ca channel blockers (slow) so slow pacemaker tissue

Question 27

Are class IV negative chronotropes or inotropes?

Answer 27

Both

Question 28

What class of drug is diltiazem?

Answer 28

IV

Question 29

What class of drug is amiodarone?

Answer 29

III

Question 30

What are the effects of diltiazem?

Answer 30

anti-arrhythmic, contractility and vasodilator

Question 31

When is diltiazem contraindicated?

Answer 31

CHF

Question 32

What can precede atrial fibrillation?

Answer 32

Atrial flutter

Question 33

How do you treat atrial flutter?

Answer 33

Glycosides and K+

Question 34

What should you always measure before giving cardiac drugs?

Answer 34

K - correcting this can fix arrhythmia

Question 35

Which drugs do you give to treat bradycardias (sinus, SA arrest, AV block)?

Answer 35

Atropine, SA arrest, AV block

Question 36

What do you give cats for thromboembolism?

Answer 36

Heparin in emergency or aspirin/clopidogrel