Alpha blockers

Question 1

What are the common indications for alpha blockers? (2)

Answer 1

1- 1st line in BPH lifestyle changes are not sufficient (can add 5a-reducatse inhibitors or surgery)
2- Add on treatment for resistant HTN when other meds insuff

Question 2

What are some examples of alpha blockers?

Answer 2

Doxazosin, tamsulosin and alfuzosin (-osin)

Question 3

What is the mechanism of action of alpha blockers?

Answer 3

> Most drugs in this class are highly selective for a1-adrenoceptors
> These receptors usually found in smooth muscle (including blood vessels of urinary tract)
> Blocker causes vasodilatation= fall in BP and reduced resistance to bladder outflow

Question 4

What are some important adverse effects of these types of meds?

Answer 4

> Postural hypotension
Dizziness
Syncope
(particularly after 1st dose)

Question 5

Warnings with a-blockers?

Answer 5

Not suitable in patients that already have hypotension

Question 6

Important interactions?

Answer 6

> Combined with other antihypertensives can cause BP lowering effects (may be wanted)
To avoid 1st dose hypo- can omit dose of other hypertensives esp B-blockers which inhibit reflex tachy

Question 7

Which alpha blocker is licensed for both indications?

Answer 7

> Doxazosin- start 1mg then increase in 1-2 week intervals

Question 8

How is tamsulosin Rx?

Answer 8

> Only licensed for BPH (not as good for BP lowering)

> 400mcg OD

Question 9

When is it best to take Doxasozin?

Answer 9

At night due to BP lowering effect (esp initially)

Question 10

What is the best measure of the meds efficacy?

Answer 10

Either BP or urinary symptoms (depending on indication)

Question 11

What are the common forms?

Answer 11

Tablets- also comes in MR form but no evidence that improves compliance because normal tabs are once daily too