Urology

Question 1

Name 2 alpha blockers

Answer 1

Doxazosin, Tamsulosin

Question 2

What is the mechanism by which alpha blockers/doxazosin/Tamsulosin work?

Answer 2

• Alpha1 adreno-receptors present in smooth muscle of blood vessels and urinary tract (bladder neck, prostate)
• Blocking alpha1 adrenoreceptors causes smooth muscle relaxation
• Causes vasodilation of blood vessels, reducing BP and relaxation of urinary tract smooth muscle, reducing urine outflow obstruction

Question 3

What are the indications for Doxazosin & Tamulosin/Alpha blockers?

Answer 3

• 1st line treatment in relieving Sx of BPH when lifestyle managment strategies have failed. Can be combined with 5 reductase inhibitors too!
• Add on treatment in resistant hypertension when other drugs (ACEi, Ca channel blockers, thiazide diuretics) failed

Question 4

What are the contraindications for alpha blocker/doxazosin & Tamsulosin?

Answer 4

Hypotension (existing) - can worsen Sx

Question 5

What are the SEs of alhpa blockers/doxazosin/tamsulosin

Answer 5

Hypotension - dizziness, postural hypotension, syncope - particularly bad in BPH age group who = older (increased risk of falls and fragility #)

Question 6

What are the potential interactions of alpha blocker/doxazosin/tamsulosin?

Answer 6

In combination with other other anti-hypertensive meds can have additive effect on hypotension (especially first dose)

Question 7

How is alpha blockers/doxazosin/tamsulosin eliminated?

Answer 7

Hepatically

Question 8

Name one 5 alpha reductase inhibitor drug

Answer 8

FInasteride

Question 9

What is the mechanism by which finasteride/5a reductase blockers work?

Answer 9

Testosterone —5a reductase —> Dihydrotestosterone

Dihydrotestosterone is more active metabolite and causes prostate growth

Therefore, blocking 5a reductase reduces prostate growth and improves urinary flow

Question 10

What are the indications for 5 a reductase inhibitors

Answer 10

1. 2nd line for BPH (1st line is alpha blockers/doxazosin, tamsulosin) because it takes a few months to take effect).

Question 11

What are the CIs of finasteride/5a reductase inhibitors

Answer 11

Can cause abnormal development of male foetus genitalia. Therefore, pregnant women should not take finasteride and avoid its exposure (i.e. found in semen during unprotected sex)

Question 12

What are the SEs of finasteride/5a reductase blockers?

Answer 12

• impotence (transient)
• Reduced labido
• Breast development/enlargement (gynaecomastia)
• Hair growth
• Reduced PSA levels (cautioned in cancer monitoring)
• Breast cancer in men has been reported when taking 5a reductase inhibitors

Question 13

What are the important drug interactions of 5a reductase inhibitors?

Answer 13

none important

Question 14

How is 5a reductase excreted?

Answer 14

Renal (40%), Feces (60%)