Verapamil

Question 1

Class

Answer 1

Class 4 antidysrhythmic

Question 2

Actions

Answer 2

Antianginal and
antihypertensive
Blocks Ca2+ channels in
both cardiac and
smooth muscles so has
both negative inotropic
and smooth muscle
relaxant actions

Question 3

Mechanism of action

Answer 3

Blocks L-type voltage-
gated Ca2+ channels which
are important in the action
potential plateau and in
particular affects action
potential in the SAN and
AVN.
Decreases automaticity
Slows AV conduction

Question 4

Clinical use

Answer 4

Supraventricular
tachycardia
Control of ventricular
rate in atrial
fibrillation

Question 5

Adverse effects

Answer 5

Side effects are caused
by smooth muscle
relaxation
Hypotension
Dizziness
Ankle oedema
Constipation
Heart block
Bradycardia

Question 6

what is Verapamil classed as

Answer 6

A Class IV anti-arrhythmia agent (A calcium channel blocker)

Question 7

what does Verapamil inhibit

Answer 7

voltage-dependent calcium channels

Question 8

what does Verapamil do in the heart

Answer 8

blocks the L-type calcium channels causing a reduction in ionotropy and chronotropy, reducing heart rate and blood pressure

Question 9

what are the two enantiomers of Verapamil

Answer 9

The R-enantiomer and the s-enantiomer

Question 10

what is the difference between the R-enantiomer and the S-enantiomer

Answer 10

The R-enantiomer is more effective at reducing blood pressure compared to the S-enantiomer. However, the S-enantiomer is 20 times more potent than the R-enantiomer at prolonging the PR interval in treating arrhythmias.

Question 11

how often is verapamil used

Answer 11

not commonly

Question 12

how is Verapamil administered

Answer 12

IV only