Beta blockers

Question 1

What are SEVEN indications?

Answer 1

Ischaemic heart disease: to improve symptoms and prognosis in angina and ACS

Chronic heart failure: to improve prognosis

AF

SVT

Resistant hypertension- fourth line

prophylaxis of migraine

thyrotoxicosis

Question 2

What is the mechanism of action?

Answer 2

block the release of adrenaline and noradrenaline in the heart, peripheral vasculature, bronchi, pancreas and liver.

This results in a slowing of the heart rate and reduces the force at which blood is pumped around your body.

Question 3

What are common side effects?

Answer 3

Fatigue,
cold extremities,
headache
GI upset are common. sleep disturbances nightmares
impotence
Hyper/hypoglycaemia

Question 4

Who should be prescribed with caution/avoided?

Answer 4

Asthma- can cause life threateningbronchospasm

Safe in COPD but important to choose relatively 1-selective option: bisoprolol, metoprolol

Caution:
-heart failure: may initially impair cardiac function. Start on a low dose and increase slowly
-Diabetes.
-Myasthaenia gravis.
-Portal hypertension — due to risk of deteriorating liver function.
-Psoriasis.

Reduce dosage in hepatic failure

Question 5

What are they contraindicated in?

Answer 5

heart block
severe hypotension
Bradycardia

Question 6

What are common interactions?

Answer 6

Non dihydropyridine CCB -

Can cause heart failure, bradycardia and asystole

Question 7

What are dosages for each beta blocker for hypertension

Answer 7

Atenolol
The usual dose is 25–50 mg daily (single dose).
If necessary, increase doses at an interval of 2 weeks.
max 100 mg OD

Bisoprolol
5mg daily initial
10 mg daily (single dose taken in the morning).
max 20 mgOM

Carvedilol
Initial 12.5 mg once daily for 2 days, then increase to 25 mg once a day
(12.5 mg daily may provide adequate control in elderly people).
Max is 50 mg daily, in single or divided doses.
Increase doses above 25 mg at an interval of at least 2 weeks.

Propranolol
Initial 80 mg BD
If necessary, increase doses at weekly intervals. The usual dose is 160–320 mg daily.

Question 8

What are monitoring and stopping requirements?

Answer 8

In ischaemic heart disease, aim for a resting heart rate of around 55–60beats/min.

During initiation and titration of a β-blocker in heart failure, daily measurement of body weight can be useful.

In established treatment, if the β-blocker needs to be stopped the dose should be reduced gradually over 1–2weeks. Can lead to myocardial ischaemia.

Question 9

Why is it best to prescribe a beta blocker that has a short half life when starting acutely?

Answer 9

it will be more responsive to dosage adjustments and can be stopped quickly if needed

e.g oral metoprolol in ACS
Dosage: 12.5mg TDS; later increased to 25mg TDS.