Alpha blockers

Question 1

Mechanism of action, alpha blockers ?

Answer 1

Broadly described as alpha blockers, most of them are highly selective for the adrenceptors mainly present in smooth muscle : blood vessel and urinary tract. Since the stimulation induces contraction, blockade causes relaxation.
a-blockers consequently cause :
-vasodilatation;
-fall in blood pressure,
-reduced resistance to bladder outflow.

Question 2

Indications of a-blockers ?

Answer 2

• First line medical option in benign prostate hyperplasia

- Add-on treatment in resistant HT.

Question 3

Important AE ?

Answer 3

postural hypotension, dizziness and syncope (particularly prominent after the first dose)

Question 4

Important warnings ?

Answer 4

Should not be used in patients with existent postural hypotension.

Question 5

Name the most prescribed a-blockers ?

Answer 5

Prazosine
Urapidil
Doxazosin
Tamsulosin

(do not mess up, a-methyl dopa &clonidie are a-2 agonists &not blockers)

Question 6

How is doxazosin prescribed ?

Answer 6

Doxazosin is licensed for both : benign prostate hyperplasia and hypertension.
Doxazosin is typically started at a dose of 1 mg daily, and increased at 1-2 weeks according to response.
Tamsulosin : 400 mg daily.
Best to take at bed time.

Question 7

How is Tamsulosin prescribed ?

Answer 7

Tamsulosin is only licensed for BPH. It is given in a dose of 400 mg daily.
Best to take at bed time.