CV: Calcium Channel Blockers

Question 1

Which CCB should usually be avoided in heart failure because they may further depress cardiac function and cause clinically significant deterioration?

Answer 1

Verpamil and diltiazem the non-dihydropyridine CCBS

Question 2

The most common side effect of verapamil

Answer 2

Constipation

Question 3

What is verapamil used in the treatment of? (3)

Answer 3

Angina
Hypertension
Arrhythmias

Question 4

What is the activity of verapamil?

Answer 4

Verapamil is highly negatively inotropic and it reduces cardiac output, slows the heart rate and may impair atrioventricular conduction.

Question 5

What are the side effects/adverse effects of verapamil?

Answer 5

Verapamil can precipitate heart failure, exacerbate conduction disorders, cause hypotension at high doses and should NOT be used with BBs.

Most common side effect is constipation.

Question 6

What is the activity of nifedipine?

Answer 6

Relaxes vascular smooth muscle and dilates coronary and peripheral arteries.

It has more influence on vessels and less on the myocardium than verapamil, and also unlike verapamil has no anti-arrhythmic activity.

Question 7

Why does nifedipine rarely precipitate heart failure?

Answer 7

Any negative inotropic effect is offset by a reduction in left ventricular work.

It has more influence on vessels and less on the myocardium than verapamil.

Question 8

Which CCBs all have similar effects and do not reduce myocardial contractility and do not produce clinical deterioration in heart failure?

Answer 8

Amlodipine, felodipine, nifedipine, nicardipine.

Question 9

Nifedipine, nicardipine, amlodipine and felodipine are used for the treatment of what? (2)

Answer 9

1. Angina
   OR
2. Hypertension

Question 10

Nifedipine, nicardipine, amlodipine and felodipine have what side effects?

Answer 10

Side-effects associated with vasodilatation such as flushing and headache (which become less obtrusive after a few days), and ankle swelling (which may respond only partially to diuretics) are common.

Question 11

Lacidipine and lercanidipine have similar effects to those of nifedipine and nicardipine but are indicated to the treatment of what only?

Answer 11

Hypertension

Question 12

Nimodipine is related to nifedipine but the smooth muscle relaxant effect preferentially acts on what arteries?

Answer 12

The cerebral arteries.

Nimodpine use is confined to prevention and treatment of vascular spasm following aneurysmal subarachnoid haemorrhage.

Question 13

Diltiazem is effective in most forms of angina and the longer-acting formulaton is used for what?

Answer 13

Hypertension

Question 14

Diltiazem may be used in patients for whom BBs are contra-indicated or inffective.

Its activity differs from verapamil how?

Answer 14

It has less negative inotropic effects than verapamil and as a result significant myocardial depression occurs rarely.

Still the risk of bradycardia means it should not be used in association with beta blockers.

Question 15

CCB work at what _-type calcium channel?

Answer 15

L type (and t-type, see ethosuximide which is an antiepileptic used to treat absence seizures which works at the T-type CC.)

Question 16

CCB have what four effects?

Answer 16

1. Increased arterial diameter - do NOT affect venous diameter.
2. Lessen the force of cardiac contraction.
3. Slow both the conduction of electrical activity and hearbeat.
4. Reduce aldosterone production and, consequently, blood pressure.

Question 17

What CCBs can cause gingival enlargement?

Answer 17

1. Nifedipine
2. Verapamil
3. Amlodipine

Ciclosporin + phenytoin account for 80% cases.

(Lamotrigine, ethosuximide and topiramate also cause it)

Question 18

What CCB is used in palliative care for hiccup?

Answer 18

Nifedipine:

Not for use in Crohns.

Question 19

What are the implications of CCB inhibiting aldosterone production?

Answer 19

Aldosterone is the main mineralocorticoid hormone and is essential for sodium conservation in the kidney, salivary glands, sweat glands and colon.

Question 20

Which of the following is incorrect about CCB?

Lessen the force of cardiac contraction
Inhibit aldosterone production
Increase arterial and venous diameter

Answer 20

They only increase arterial NOT venous diameter

Question 21

Most clinically used CCBs - such as amlodpine and verapamil - exert their effects at which type calcium channel?

T-type
L-type
N-type

Answer 21

L-Type.

N-type channels are blocked in the treatment of pain, this is the mechanism of action of the drug ziconotide:

A non-opioid analgesic administered by intrathecal infusion (ziconotide (Prialt®), available from Eisai) is licensed for the treatment of chronic severe pain; ziconotide can be used by a hospital specialist as an adjunct to opioid analgesics.

Question 22

Which CCB has the longest half life? Why is this?

Answer 22

Amlodipine has a long half-life - usually between 1 and 2 days - because it has a high volume of distribution and slow liver metabolism.

Also, amlodipine does not undergo significant first-pass
metabolism.

Question 23

Can amlodipine be used in breastfeeding mothers?

Answer 23

No.

Also contraindicated in cardiogenic shock, unstable angina and aortic stenosis.

Question 24

Should diuretic be used for treating peripheral oedema resulting from CCB use?

Answer 24

No,
They are very much limited in this use, peripheral odema caused by CCB use is stubborn and most likely CCB will need to be stopped.