alpha blockers Flashcards
What are the 2 main common indications for the use of alpha blockers?
1) First line medical option to improve symptoms in BPH, when lifestyle changes are insufficient
2) As an add-on treatment in resistant HTN when other medicines are insufficient.
1) What may be added to alpha blockers in select cases of BPH?
2) What receptors are most drugs termed ‘alpha blockers’ highly selective for?
1) 5-alpha reductase inhibitors.
2) Highly selective for alpha-1 adrenoreceptors.
1) Where are alpha-1 adrenoreceptors mainly found?
2) What does stimulation of alpha-1 receptors cause?
3) What does blockade of alpha-1 receptors induce?
1) In smooth muscle including in blood vessels and the urinary tract (the bladder neck and prostate in particular).
2) Stimulation of alpha-1 receptors causes contraction.
3) Blockade of alpha-1 receptors induces relaxation.
What are the 2 main overall effects of alpha-blockers?
They cause vasodilation and a fall in blood pressure, and reduced resistance to bladder outflow.
1) Give the 3 main adverse effects of alpha-blockers?
2) When are adverse effects of alpha-blockers more prominent?
3) In what patients should alpha-blockers not be used in?
1) Postural hypotension, dizziness and syncope (due to their effects on vascular tone).
2) After the first dose.
3) Should not be used in patients with existing postural hypotension.
1) Generally, what does combining antihypertensive drugs result in?
2) What might be done to avoid pronounced first dose hypotension with alpha blockers?
1) Additive blood pressure lowering effects (which may well be the therapeutic aim).
2) May be prudent to omit doses of one or more existing antihypertensive agent on the day the alpha-blocker is started.
1) Why is it particularly important to omit a dose of beta-blocker when starting a patient on alpha-blockers?
1) Because beta-blockers inhibit the reflex tachycardia that forms part of the compensatory response to vasodilation.
1) What are the most commonly prescribed alpha-blockers in the UK?
2) Which alpha-blocker is licensed for both BPH and hypertension?
3) Why is it best to take Doxazosin at night?
1) Doxazosin and Tamsulosin.
2) Doxazosin.
3) Due to the pronounced blood pressure lowering effect of doxazosin, so is better to take doxazosin at night, at least initially.
