Beta blockers

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How they work

They are a cardiac drug that block beta (β) receptors in the heart. This means that the heart slows down (negative chronotropic effect), and pumps less hard (negative inotrophic effect). Some types are selective, such as propanolol, and only work on β1 receptors, reducing the side effects resulting from blockage of β2 receptors, but not completely. Atenolol was the first one, but rarely used these days.

What are they used for

Common types and dose

Atenolol is very well known, but not really used that much these days. Instead, try:

  • Bisoprolol hypertension and angina 1.25mg-5mg OD upto 10mg.
  • Propanolol hypertension 160-320mg OD, angina and arrhythmias upto 40mg QDS. Good for anxiety and headaches, as it crosses blood brain barrier. Also give it after MI, as its proven to reduce death.
  • Sotalol prophylaxis for AF, ventricular arrhythmias and SVT 160-320mg BD - in life threatening situations, upto 640mg.

Side effects

They should not be used on patients with asthma, since they can cause bronchospasm. Whilst some b1 blockers are slightly better in this regard, they still should not be used, apart from in a few weird and wonderful situations that you don't need to know about.

They are also contraindicated in heart block, since they can cause or worsen it.

Patients sometimes complain of feeling light headed, or even losing consciousness. This implies the beta blockers are working a little too well, and it's time to cut the dose.