GU: Alpha blockers, Anti-muscarinics

Question 1

Indications of alpha blockers?

Answer 1

Benign prostatic enlargement (1ST LINE)

Resistant hypertension (if other meds are insufficient)

Question 2

MOA of alpha blockers?

Answer 2

Alpha1-blockers bind to alpha1-adrenoreceptor, which found in smooth muscles in blood vessels and the urinary tract.
→ this causes vasodilation and reduces BP, and reduces resistance to bladder outflow.

Question 3

Examples of alpha blockers?

Answer 3

doxazosin
tamsulosin
alfuzosin

Question 4

Adverse effects of alpha blockers?

Answer 4

Postural hypotension
Dizziness
Syncope

(esp after first dose)

Question 5

Warnings of alpha blockers?

Answer 5

Avoid in postural hypotension.

Question 6

Interactions of alpha blockers?

Answer 6

Combining antihypertensive drugs:
→ additive BP lowering effects​

To avoid pronounced first-dose hypotension, leave out doses of one or more existing antihypertensive drugs on the day the alpha-blocker is started​, particular the BB.
→ BB inhibits the reflex tachycardia that forms part of the compensatory response to vasodilation.

Question 7

Monitoring of alpha blockers?

Answer 7

Efficacy:
Improvement in urinary symptoms.
Reduction in BP

Safety and tolerability:
Assessing postural blood pressure.

Question 8

Pt education of alpha blockers?

Answer 8

Aims to treat their urinary symptoms or lower their blood pressure.

May cause dizziness on standing, esp after first dose.
→ take med at bedtime to minimise the impact of this.

If they need to get out of bed, they should rise from bed slowly.

Question 9

Indications of anti-muscarinics?

Answer 9

Treats overactive bladder
e.g. polyuria, urgency, urge incontinence

Question 10

MOA of anti-muscarinics?

Answer 10

Competes with acetylcholin and binds to muscarinic receptors.

Blocking muscarinic M3 receptors causes:
- bladder relaxation, increasing bladder capacity.
→ this reduces urinary frequency, urgency, and urge incontinence.

Question 11

Examples of of anti-muscarinics?

Answer 11

oxybutynin
tolterodine
solifenacin

Question 12

Adverse effects of anti-muscarinics?

Answer 12

GI disturbance:
- Dry mouth
- Constipation
- Urinary retention (if bladder outflow obstruction)

Blurred vision
Tachycardia

Question 13

Warnings of anti-muscarinics?

Answer 13

Avoid in UTI.

Use with caution in pts:
- elderly and dementia (due to SEs like drowsiness and confusion)
- susceptible to acute angle closure glaucoma (can increase intraocular pressure)
- at risk of arrhythmias
- risk of urinary retention

Question 14

Interactions of anti-muscarinics?

Answer 14

Adverse effects increased if combined with other antimuscarinic effect (e.g. tricyclic antidepressants).

Question 15

Monitoring of anti-muscarinics?

Answer 15

Urinalysis before starting tx.

Review pt after a month of starting tx.
Assess side effects and response.

Question 16

Pt education of anti-muscarinics?

Answer 16

Aims to relax the bladder.

Aims to reduce how often you pass urine, the urgency, and accidents.

Dry mouth is a common SE.

Elderly pts -may cause drowsiness and confusion.