Membrane stabilising drugs

Question 1

How many classifications of anti-arrhythmic drugs are there and what are they???

Answer 1

4 classes

Class 1 - Block Na+ channels
Class 2 - Beta-adrenoreceptor antagonists
Class 3 - Prolong action potential and prolong refractory period
Class 4 - Ca2+ channel antagonists.

Question 2

What do class 1 drugs do???

Answer 2

They block sodium channels.
They exist in 3 states which are resting, open and refractory.
There are classes a,b and c for sodium channel blockers and the actions depends on the class.

Question 3

What is an example of class 1a drug???

Answer 3

Procainamide

Binds to a open or inactivated sodium channel.
Prolongs repolarisation

Question 4

What is an example of a class 1b drug???

Answer 4

Lidocaine

Blocks inactivated sodium channels rather than open.
It has a rapid onset and short duration of action.

Question 5

What is an example of a class 1c drug???

Answer 5

Flecainide

Non-selective binding to sodium channels.
Longer acting, meaning it supresses re-entrant rhythms

Question 6

What are example of calcium channel blockers?

Answer 6

Gabapentin
Pregabalin

Used for treating chronic neuropathic pain.

Question 7

What are example of sodium channel blockers?

Answer 7

Carbamazepime.
Oxcarbazepine.
Topiramate.