Benign Prostatic Hyperplasia

Question 1

Alpha-blockers

Common indications

Answer 1

1. As a first-line option to improve symptoms in benign prostatic hyperplasia, when lifestyle changes are insufficient 5a-reductase inhibitors may be added in selected cases
   * Surgical treatment is also an option, particularly if there is evidence of urinary tract damage (e.g. hydronephrosis)
2. As an add on treatment in resistant hypertension when other medicines (CCB, ACEI, diuretics) are insufficient

Question 2

Alpha-blockers

MOA

Answer 2

• Although often described using the broad term ‘a-blocker’, most drugs in this class (e.g. doxazosin, tamsulosin and alfuzosin) are highly selective for the a1-adrenoceptor
• a1-adrenoceptors are found mainly in smooth muscle, including in blood vessels and the urinary tract (bladder, neck and prostate in particular)
• Stimulation induces contraction; blockade induces relaxation
• a1-blockers, therefore, cause vasodilation and a fill-in BP and reduce resistance to bladder outflow

Question 3

Alpha-blockers

Adverse effects

Answer 3

• Predictably from their effects on vascular tone, a-blockers can cause postural hypotension, dizziness and syncope
• This is particularly prominent after the fist dose (rather like with ACEI and ARB’s)

Question 4

Alpha-blockers

WARNINGS

Answer 4

• Alpha-blockers should not be used in patients with existing postural hypotension

Question 5

Alpha-blockers

Interactions

Answer 5

• In general, combining. antihypertensive drugs result in additive BP-lowering effects (this may well be the therapeutic aim)
• To avoid pronounced first-dose hypotension, it may be prudent to omit doses of one or more existing anti-hypertensive drugs on the day the a-blocker is started
• This is particularly the case of BB, which inhibit the reflex tachycardia that forms part of the compensatory response to vasodilation

Question 6

5a-reductase inhibitors

Common indications

Answer 6

• In benign prostatic hyperplasia, 5a-reductase inhibitors are a second-line medical treatment after a-blockers
• They improve lower urinary tract symptoms, such as difficulty passing urine, urinary retention and poor urinary flow, and reduce the need for prostate-related surgery

Question 7

5a-reductase inhibitors

MOA

Answer 7

• 5a-reductase inhibitors reduce the size of the prostate gland They do this by inhibiting the intracellular enzyme 5a-reductase, which converts testosterone to its more active metabolite dihydrotestosterone
• As dihydrotestosterone stimulates prostatic growth, inhibition of its production by. 5a-reductase inhibitors reduces prostatic enlargement and improves urinary flow
• However, it can take several months for this effect to become evident clinically
• For this reason, an a-blocker is usually preferred for initial therapy, with 5a-reductase inhibitors added if the response if poor or if the prostat.e is particularly bulky

Question 8

5a-reductase inhibitors

Adverse effects

Answer 8

• The most common adverse effects of 5a-reductase inhibitors relate to their anti-androgen action
• These include impotence and reduced libido, which are usually transient, and breast tenderness and enlargement (gynaecomastia), which can affect patient adherence to treatment.t
• An additional effect of androgen inhibition is hair growth, which can be exploited to advantage inthe treatment of male-pattern baldnesss
• Breast cancer has been reported in men taking finasteride

Question 9

5a-reductase inhibitors

Warnings

Answer 9

• Exposure of a male foetus to 5a-reductase inhibitors may cause abnormal development of the external genitalia
• It is therefore important that pregnant women do not take these drugs and are not exposed to them
• e.g. by handling broken or damaged tablets or through semen during unprotected intercourse with a man taking these drugs

Question 10

5a-reductase inhibitors

Communication

Answer 10

• Explain to the patient that the reason he is having difficulty passing urine is because his prostate has grown and is squashing the ureter
• Tell him that finasteride treatment will make his prostate shrink, which will open up the tube and make it easier to wee
• However it may take up to 6 months before symptoms improve
• Main side effects: loss of libido, erectile dysfunction, gynaecomastia, breast cancer
• If the patients partner becomes pregnant, wear a condom during intercourse to protect the baby from the effects of the drugs