Alpha Blockers

Question 1

What are the selective alpha blockers?

Answer 1

Prazosin (minipress)

Terazosin

Question 2

What are the counseling points of selective alpha blockers?

Answer 2

• dizziness on standing may occur especially when starting treatment or when the dose is increased. Get up gradually from sitting or lying to minimise this effect; sit or lie down if you become dizzy.
• take the first dose at bedtime, but be careful if you get up during the night as you may feel dizzy
• this medicine may cause drowsiness or dizziness; do not drive or operate machinery if affected
• tell your ophthalmologist you are taking, or have taken, this medicine if you are going to have cataract surgery

Question 3

What are the dose ranges of selective alpha blockers?

Answer 3

Prazosin(Minipress):
0.5mg bd to 20mg d (2/3 doses)

Terazosin:
1mg–20mg d

Question 4

What is the indication of selective alpha blockers?

Answer 4

HTN

Question 5

What are the practice points of selective alpha blockers?

Answer 5

> start additional antihypertensives cautiously as BP may fall sharply
first dose hypotension is most serious in:
- the elderly
- those with fluid depletion
- on diuretics
THEREFORE to minimise it:
- start with a small dose of the selective alpha-blocker given before bedtimeincreasing
- increase dose slowly (at 2-week intervals)
- withhold diuretic for a few days before starting the selective alpha-blocker
- reduce dose of calcium channel blocker/beta-blocker before starting the selective alpha-blocker