Calcium-Channel Blockers

Question 1

Why should calcium channel blockers (with the exception of amlodipine) be avoided in heart failure? (2)

Answer 1

• They can further depress cardiac function and exacerbate symptoms.
• They can also increase mortality after myocardial infarction in patients with left ventricular dysfunction and pulmonary congestion

Question 2

What are the indications for Verapamil hydrochloride? (5)

Answer 2

• Treatment of supraventricular arrhythmias
• Paroxysmal tachyarrhythmias
• Angina
• Hypertension
• Prophylaxis of cluster headache (initiated under specialist supervision)

Question 3

What is the dosing of Verapamil for the treatment of supreventricular arrhythmias by PO and IV in adult and elderly people?

Answer 3

PO:
40–120 mg 3 times a day for Adult

IV:

• 5–10 mg, to be given over 2 minutes, preferably with ECG monitoring for Adult
• 5–10 mg, to be given over 3 minutes, preferably with ECG monitoring

Question 4

What is the dosing of Verapamil for the treatment of Paroxysmal tachyarrhythmias by IV in adult and elderly people?

Answer 4

Adult:
- 5–10 mg, followed by 5 mg after 5–10 minutes if required, to be given over 2 minutes, preferably with ECG monitoring.

Elderly:
- 5–10 mg, followed by 5 mg after 5–10 minutes if required, to be given over 3 minutes, preferably with ECG monitoring.

Question 5

What is the dosing of Verapamil for the treatment of Angina by PO?

Answer 5

Adult:

- 80–120 mg 3 times a day.

Question 6

What is the dosing of Verapamil for the treatment of Hypertension by PO?

Answer 6

Adult:

- 240–480 mg daily in 2–3 divided doses.

Question 7

What is the dosing of Verapamil for the treatment of Prophylaxis of cluster headache (initiated under specialist supervision)

Answer 7

Adult:

- 240–960 mg daily in 3–4 divided doses.

Question 8

What are the contraindications for Verapamil? (8)

Answer 8

• Acute porphyrias
• Atrial flutter or fibrillation associated with accessory conducting pathways (e.g. Wolff-Parkinson-White-syndrome);
• Bradycardia;
• Cardiogenic shock;
• Heart failure (with reduced ejection fraction);
• History of significantly impaired left ventricular function (even if controlled by therapy);
• Hypotension;
• Second- and third-degree AV block

Question 9

What are the common Side Effects for Verapamil? (9)

Answer 9

• Abdominal pain;
• Dizziness & Drowsiness;
• Flushing;
• Headache;
• Nausea & Vomiting
• Palpitations;
• Peripheral oedema;
• Skin reactions;
• Tachycardia;

Question 10

Is Verapamil negatively or positively ionotrpoic?

Answer 10

Negative

• reduces cardiac output
• slows heart rate
• may impair atrioventricular conduction

Question 11

What are the indications for Nifedipine?

Answer 11

• Raynaud’s syndrome
• Angina prophylaxis (not recommended)
• Postponement of premature labour
• Hiccup in palliative care
• Chronic anal fissure

Question 12

What is the dosing of Nifedipine for the treatment of Raynaud’s syndrome by PO?

Answer 12

Initially 5 mg 3 times a day, then adjusted according to response to 20 mg 3 times a day.

Question 13

What is the dosing of Nifedipine for the treatment of Angina prophylaxis (not recommended) by PO?

Answer 13

Initially 5 mg 3 times a day, then adjusted according to response to 20 mg 3 times a day.

Question 14

What is the dosing of Nifedipine for the treatment of Postponement of premature labour by PO?

Answer 14

Initially 20 mg, followed by 10–20 mg 3–4 times a day, adjusted according to uterine activity.

Question 15

What is the dosing of Nifedipine for the treatment of Chronic anal fissure by PR and PO?

Answer 15

PR:
Apply 2–3 times a day until pain stops. Max. duration of use 8 weeks, apply to anal canal, using 0.2%–0.5% topical preparation.

PO:
20 mg twice daily until pain stops. Max. duration of use 8 weeks.

Question 16

What are the contraindications of Nifedipine? (5)

Answer 16

With systemic use:
- Acute attacks of angina;

• Cardiogenic shock;
• Significant aortic stenosis;
• Unstable angina;
• Within 1 month of myocardial infarction

Question 17

What are the common side effects of Nifedipine?

Answer 17

• Constipation;
• Malaise;
• Oedema;
• Vasodilation

Question 18

What are the effects of Nifedipine in pregnancy?

Answer 18

May inhibit labour

Avoid use before week 20

Use only if other treatment options are not indicated or have failed

Question 19

What could a patient expect if they ceased treatment of Calcium Channel Blockers completely and immediately?

Answer 19

Sudden withdrawal of calcium-channel blockers may be associated with an exacerbation of myocardial ischaemia

Question 20

What are the indications for Diltiazem hydrochloride?

Answer 20

Prophylaxis and treatment of angina:
- 60 mg PO 3 times a day; max 360 mg per day

Chronic anal fissure

• 60 mg PO BD until pain stops. Max duration 8 weeks
• 2% topical preparation BD until pain stops. Max duration 8 weeks

Question 21

What are the contraindications of Diltiazem hydrochloride? (8)

Answer 21

Acute porphyrias;

Cardiogenic shock;

Heart failure (with reduced ejection fraction);

Left ventricular failure with pulmonary congestion;

Second- or third-degree AV block (unless pacemaker fitted);

Severe bradycardia;

Sick sinus syndrome;

Significant aortic stenosis

Question 22

What are the common side effects for all Calcium Channel Blockers? (11)

Answer 22

Abdominal pain;

Dizziness;

Drowsiness;

Flushing;

Headache;

Nausea;

Palpitations;

Peripheral oedema;

Skin reactions;

Tachycardia;

Vomiting

Question 23

What are the indications and dose of Amlodipine?

Answer 23

Prophylaxis of Angina:
- 5mg OD PO, maximum 10 mg per day

Hypertension:
- 5 mg OD PO maximum 10 mg per day

Question 24

What are the contraindications for Amlodipine?

Answer 24

Cardiogenic shock

Significant aortic stenosis

Unstable angina

Question 25

What could happen with a sudden withdrawal of calcium channel blockers?

Answer 25

An exacerbation of Myocardial Ischaemia

Question 26

What are the indications and dose of Felodipine?

Answer 26

Prophylaxis of Angina
- 5 mg OD PO, increased to 10 mg OD, taken in the morning

Hypertension
- 5 mg OD PO, usual maintenance 5-10 mg OD

Question 27

What are the contraindications for Felodipine? (5)

Answer 27

Cardiac outflow obstruction

Significant cardiac valvular e.g. aortic stenosis

Uncontrolled heart failure

Unstable angina

Within 1 month of MI