IHD AND CHF Drugs: Beta blockers

Question 1

Beta blockers drugs?

Answer 1

1. Non-selective: Propranolol
2. β1 (cardiac) selective: Atenolol
3. β2 (respiratory) selective: Butaxamine
4. α + β Blockers: Labetolol

Question 2

Beta blockers mechanism of action?

Answer 2

1. Bind to β receptors causing lowered sympathetic output
2. ↓ cAMP formed
3. ↓ Sinuatrial node activity, ↓ AV conduction= ↓ HR
4. ↓ Ca2+ influx= ↓ contractility
5. ↓ Myosin Light Chain Kinase activity
   = ↓ Myosin Light chain phosphorylated
   = ↓ vascularsmooth muscle contraction
   = vasodilation
6. Maintains systolic pressure but lower diastolic pressure

Question 3

Beta blockers side effects?

Answer 3

1. Hypotension when overdosed
2. Bradycardia and possible heart block
3. Erectile dysfunction
4. CNS disturbances – mild sedation

Question 4

Beta blockers Contraindicated in?

Answer 4

1. Type 1 Diabetes Mellitus px (hypoglycaemia)

2. Asthma patients (bronchoconstriction)