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Beta blockers

block beta-adrenergic receptors
some have selectivity for beta-1 or beta-2 receptors
b-blockers are used to reduce cardiac work and myocardial oxygen consumption.
They bind to b₁ adrenoreceptors within the sino-atrial node and the myocardium,
act to reduce the increase in heart rate and force of contraction
- during exercise
- times of anxiety
they also improve myocardial perfusion by prolonging diastole

intrinsic sympathomimetic activity (less cold extremities)
- oxprenolol
- pindolol
- acebutolol
- celiprolol
water-soluble (less psychiatric disturbance, more problems in renal impairment)
- atenolol
- celiprolol
- nadolol
- sotalol (may prolong QT - avoid Hypokalaemia)
vasodilating
- labetalol
- celiprolol
- carvedilol
- nebivolol
cardioselective (beta-1 antagonism > beta-2)
- atenolol
- betaxolol
- bisoprolol
- metoprolol
- acebutolol
short acting
- esmolol

Intolerance
- fatigue
- cold extremities
- sexual dysfunction
- loss of motivation
Bronchospasm: regardless of whether the drug used is cardioselective or not
CNS effects
- more common with lipid soluble drugs and include
- malaise
- vivid dreams
- nightmares
- hallucinations
Masking of hypoglycaemia
Metabolic disturbances
- increase plasma triglyceride
- decrease high density lipoprotein

well absorbed orally
lipid soluble drugs e.g. metoprolol
- absorbed more rapidly by the gut, than the lipid insoluble drugs
- experience higher presystemic metabolism in the gut wall and the liver
- once in the circulation these drugs tend to be protein bound
Polar b blockers
- excreted by the kidney without metabolism
- have longer half-lives
- not protein bound
- accumulate in renal failure
Half-life of most b blockers is short such that multiple daily dosing may be required
b₁ selective blockers are preferred because there are less side effects