beta-blockers

(redirected from beta-adrenoceptor-blocking drugs)

Beta-blockers

A class of medication used to block the cellular response to chemicals normally present in the body.

beta-blockers

; beta-adrenoceptor-blocking drugs; β-blockers agents that block beta- adrenoceptors of heart, peripheral vasculature, bronchi, pancreas and liver; often administered in conjunction with thiazide diruetics; cardiovascular effects: slow heart rate, reduce blood pressure; relieve symptoms of glaucoma; exacerbate Raynaud's; bronchial effects: exacerbate asthma; pancreatic effects: tend to impaired glucose tolerance and mask early symptoms of hypoglycaemia; hepatic effects: additive toxic effect with local anaesthetic (see also Table 1)
Table 1: Effects of stimulation of alpha, beta and dopamine receptors
ReceptorActionStimulating drug
Alpha-1 (α1); postsynapticVasoconstriction; positive inotropism; antidiuresisAdrenaline +
Noradrenaline +++
Alpha-2 (α2); presynapticVasodilatation; inhibition of noradrenaline releaseAdrenaline +
Noradrenaline +++
Dopamine +
Alpha-2 (α2); postsynapticConstriction of coronary arteries; promotion of salt and water excretionAdrenaline +
Noradrenaline +++
Dopamine +
Beta-1 (β1); postsynapticPositive inotropism; chronotropism; renin releaseAdrenaline ++
Noradrenaline ++
Isoprenaline ++
Dopamine +
Beta-2 (β2); presynapticNoradrenaline release accelerated; positive inotropism; chronotropismAdrenaline +
Isoprenaline +++
Beta-2 (β2); postsynapticVasodilatation; relaxation of bronchial smooth muscleAdrenaline +
Isoprenaline +++
Dopamine1; postsynapticVasodilatation; diuresisDopamine ++
Dopamine1; presynapticInhibits noradrenaline releaseDopamine +

Plus signs indicate degree of effect.

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