CVS: CCB, thiazide-like diuretics

Question 1

Indications of CCB?

Answer 1

HTN

Stable angina

Supraventricular arrhythmias

Question 2

MOA of CCB?

Answer 2

CCB prevent calcium ions entering vascular and cardiac cells, hence reducing conc.
- this causes relaxation and vasodilation in arterial smooth muscle, lowering arterial pressure.

Heart
CCB suppress cardiac conduction across AV node, slowing ventricular rate.
- this reduces cardiac rate, contractility, and afterload.
- as a result this reduces myocardial oxygen demand, preventing angina.

Question 3

Adverse effects of CCB?

Answer 3

For amlodipine and nifedipine, SEs are caused by vasodilation and compensatory tachycardia:
- Ankle swelling
- Flushing
- Headache
- Palpitations

For verapamil:
- Constipation
- Bradycardia
- Heart block
- Cardiac failure

All above SEs can occur for diltiazem.

Question 4

Warnings of CCB?

Answer 4

Avoid in:
- AV nodal conduction delay (can lead to complete heart block)

Avoid Amlodipine and nifedipine in:
- unstable angina (vasodilation causes reflex increase in contractility and tachycardia, which increase myocardial oxygen demand)

• severe aortic stenosis (can provoke collapse)

Caution in:
- poor left ventricular function

Question 5

Interactions of CCB?

Answer 5

Do not prescribe non-dihydropyridine CCB (e.g. verapamil, diltiazem) with BB.
- can cause HF, bradycardia, asystole.

Question 6

Monitoring of CCB?

Answer 6

To assess treatment efficacy:
- monitor BP regularly
- ask about chest pain for angina
- check pulse rate from examination or ECG
- 24 hour tape can be performed to review arrhythmias

Question 7

Pt education of CCB?

Answer 7

• Explain why CCB is prescribed depending on the indication.
• Discuss other measures to reduce cardiovascular risk, including smoking cessation.
• Discuss common side effects, particularly ankle oedema.

Question 8

Indications of thiazide-like diuretics?

Answer 8

HTN

Question 9

MOA of thiazide-like diuretics?

Answer 9

Inhibits the Na+/Cl- co-transporter in the distal convoluted tubule of the nephron.
- This prevents reabsorption of sodium and its osmotically associated water.
- Therefore, diuresis occurs and causes an initial fall in extracellular fluid volume.

• Over time, compensatory changes tend to reverse this, for e.g. activation of the renin-angiotensin system.
• The longer-term antihypertensive effect may be mediated by vasodilation.

Question 10

Adverse effects of thiazide-like diuretics?

Answer 10

• Hyponatraemia
• Hypokalaemia
• Cardiac arrhythmias
• Increase in glucose concentration
• Increase in LDL cholesterol
• Increase in triglycerides
• Impotence in men

Question 11

Warnings of thiazide-like diuretics?

Answer 11

Avoid in:
- Hypokalaemia
- Hyponatraemia

May trigger acute attacks of gout.

Question 12

Interactions of thiazide-like diuretics?

Answer 12

Efficacy reduced in:
- hypokalaemia
- hyponatraemia

Avoid combining thiazide with other drugs that lower serum potassium concentration. Or monitor electrolytes intensively.

Question 13

Monitoring of thiazide-like diuretics?

Answer 13

Efficacy:
- monitor BP
- monitor severity of oedema

Monitor serum electrolyte concentration before starting the drug, then 2-4 weeks after starting treatment, and after changes to dose.

Question 14

Pt education of thiazide-like diuretics?

Answer 14

This ‘water tablet’ treats high blood pressure and it can also help with leg swelling if patient is experiencing that.

Ask about whether they have any difficulty getting to the toilet in time as the water tablet is likely to make the patient pass water (urine) frequently (possibility due to mobility issues or sensations of urgency).

Advise that antiinflammatory drugs, like ibuprofen, can reduce the effectiveness of diuretics.

At review, ask men directly about the possible side effect of impotence.