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1

indications alpha blockers

- benign prostatic hyperplasia where lifestyle changes are insufficient. 5a-reductase inhibitors may be added
- add on rx in resistant HTN

2

mech of action alpha blockers

Majority are specific a1-adrenoceptor blockers
a1-adrenoceptors are found in mainly smooth muscle, including blood vessels and the urinary tract - bladder neck and prostate in particular.
Stimulation = contraction. Blockade = relaxation
alpha1 blockers = vasodilatation and fall in BP, and reduced resistance to bladder outflow

3

adverse effects alpha blockers

postural hypotension
dizziness
syncope
particularly prominent after 1st dose

4

contraindications and cautions alpha blockers

should not be used in pts with existing postural hypotension

5

egs alpha blockers

doxazosin
tamsulosin
alfuzosin

6

antimuscarinics, what are the GU uses?

reduce urinary frequency, urgency and urge incontinence in overactive bladder if bladder training not effective

7

mechanism of action antimuscarinic

- antimuscarininc drugs bind to muscarinic receptors, where they act as a competitive inhibitor of acetylcholine
- contraction of smooth muscle in bladder = PS control. Blocking muscarinic receptors promotes bladder relaxation inc bladder capacity = reduce frequency
- selective for M3 receptor = majority in bladder

8

adverse effects antimuscarinics

dry mouth = common
tachycardia, constipation and blurred vision are also common

9

contraindications / caution antimuscarinics

UTI infec
CNS SE's can be particularly problematic in the elderly and pts w dementia
adverse effects are more pronounced when combined w other drugs with antimuscarinic effects such as tricyclic antidepressants

10

calcium and vit D uses in GU?

used in CKD to treat and prevent secondary hyperparathyroidism and renal osteodystrophy

11

mechanism of action calcium and vit D in CKD

In severe CKD, impaired phosphate excretion and reduced activation of vit D cause hyperphosphataemia and hypocalcaemia. This stimulates secondary hyperparathyroidism, which leads to a range of bone changes called renal osteodystrophy

12

adverse effects calcium and vit D

oral calcium may cause dyspepsia and constipation
when administered IV for hyperkalaemia calcium gluconate can cause CV collapse if administered too fast

13

calcium interactions

reduces absorption of many drugs incl iron, bisphosphonates, tetracyclines and levothyroxine

14

phosphodiesterase (type 5) inhibitors uses

erectile dysfunction
primary pulmonary htn

15

phosphodiesterase (type 5) inhibitors MOA

sildenafil is a phosphodiesterase inhibitor - it is selective for PDE type 5 found in smooth muscle of corpus cavernosum of the penis and arteries of the lung
- sexual stimulation
- NO released
- No stimulates cGMP
- Causes smooth muscle relaxation = vasodilation and penile engorgement
- PDE5 is responsible for the breakdown of cGMP, so inhibiting this inc cGMP conc = improves penile blood flow and erection

16

drug name for phosphodiesterase (type 5) inhibitors uses

sildenafil (viagra)

17

warnings sildenafil

do not use in pts whom vasodilation could be dangerous e.g recent stroke, ACS, cvd

18

SEs sildenafil

relate to action as vasodilator incl flushing, headache, dizziness and nasal congestion
serious: hypotension, tachycardia and palpitations

19

indications 5a-reductase inhibitors

benign prostatic hyperplasia, second line after a-blockers

20

e.g. 5a-reductase inhibitors

finasteride

21

MOA 5a-reductase inhibitors

Reduce size of prostate gland by inhibiting the intracellular enzyme 5a-reductase which converts testosterone to its more active metabolite dihydrotestosterone
Dihydrotestosterone stimulates prostatic growth