Anti-hypersensitive - α-blockers

Question 1

Which of the following is a alpha 1 blocker that is used for hypertension due to its ability to vasodilate blood vessels and reduce PVR?

1 - Doxazosin
2 - Bisoprolol
3 - Propranolol
4 - Carvedilo

Answer 1

1 - Doxazosin

Question 2

Which of the following is the first line treatment for lower urinary tract symptoms in benign prostatic enlargement?

1 - Carvedilo
2 - Bisoprolol
3 - Propranolol
4 - Doxazosin

Answer 2

4 - Doxazosin

• alpha 1 receptors are found on the bladder neck and prostate
• when active alpha 1 receptors cause vasoconstriction
• inhibit alpha1 receptors causes relaxation

Question 3

If all of the following ACE-I, AR2B, Calcium channel blocker and/or thiazide diuretics have failed to reduce hypertension sufficiently, which of the following can be added to try and reduce the patients hypertension?

1 - losartan
2 - doxazosin
3 - indapamide
4 - bendroflumethiazide

Answer 3

2 - doxazosin

Question 4

What is the mechanism of action of doxazosin?

1 - binds and inhibits angiotensin II receptors
2 - inhibits ACE
3 - inhibit beta1 receptors
4 - inhibit alpha1 receptors

Answer 4

4 - inhibit alpha1 receptors

• alpha 1 receptors are found on smooth muscle including blood vessels, the bladder neck and prostate
• when active alpha 1 receptors cause vasoconstriction
• these drugs reduce BP and resistance to urine outflow

Question 5

What is the key adverse event that patients may experience when taking alpha1 blockers like doxazosin?

1 - postural hypotension
2 - incontinence
3 - tachycardia
4 - bradycardia

Answer 5

1 - postural hypotension

• when we stand blood is in peripheries. Baroreceptors detect this and increase vasoconstriction to return blood to the brain and upper body
• alpha receptors inhibit this vasoconstriction, so we get postural hypotension
• can also result in syncope and dizziness

Question 6

Which group of patients should alpha1 blockers be avoided in?

1 - CKD
2 - heart failure
3 - postural hypotension
4 - asthma

Answer 6

3 - postural hypotension

Question 7

If a patient is already taking other anti-hypertensive medication and you decide to prescribe doxazosin, what should you aim to do when giving the first dose?

1 - admit patient to hospital
2 - provide continued BP monitoring
3 - provide anti-diuretic
4 - stop other anti-hypertensives

Answer 7

4 - stop other anti-hypertensives

• avoids hypotension

Question 8

In patients prescribed an a-blocker with other anti-hypertensives are often told to stop other anti-hypertensives on the day they begin taking a-blockers. What is this also important if a patient is taking a b-blocker?

1 - increases reflex tachycardia due to hypotension
2 - increases respiratory drive
3 - decreases heart rate
4 - decreases reflex tachycardia due to hypotension

Answer 8

4 - decreases reflex tachycardia due to hypotension

• if BP drops due to vasodilation causes by a-blocker, the b-blocker inhibits the reflex tachycardia and increases the risk of postural hypotension

Question 9

Patients who may be prescribed alpha1 blockers like doxazosin for hypertension and UTI symptoms in benign prostatic enlargement. However, these patients may also suffer with what that is often associated with UTI symptoms in benign prostatic enlargement?

1 - haematuria
2 - erectile dysfunction
3 - constipation
4 - tachycardia

Answer 9

2 - erectile dysfunction

Question 10

Patients who may be prescribed alpha1 blockers like doxazosin for hypertension and UTI symptoms in benign prostatic enlargement. However, these patients may also suffer with erectile dysfunction and be prescribed phosphodiesterase type 5 (PDE5) inhibitors, which increases cGMP and thus increase nitric oxide. Why do we need to be aware if patients are on both a-blockers and phosphodiesterase type 5 (PDE5) inhibitors?

1 - hypertension
2 - hypotension
3 - constipation
4 - tachycardia

Answer 10

2 - hypotension
- phosphodiesterase type 5 (PDE5) inhibitors increase cGMP and nitric oxide and cause vasodilation

Question 11

What is typically the starting dose of the alpha1 blockers like doxazosin for hypertension or UTI symptoms in benign prostatic enlargement?

1 - 1mg OD
2 - 5mg OD
3 - 10mg OD
4 - 20mg OD

Answer 11

1 - 1mg OD

• needs to be reviewed after 1-2 weeks where the dose may be increased
• generally encouraged to be taken at bedtime

Question 12

When prescribing alpha1 blockers like doxazosin for hypertension or UTI symptoms in benign prostatic enlargement, we must assess postural hypotension. This is assessed by:

• patient lies still for 5 minutes
• BP is assessed after 5 minutes
• patient stands up and BP measured in the 1st minute
• patient remains standing and BP measured again after 3 minutes

Answer 12

• a drop in SBP of >20 with or without symptoms indicated postural hypotension