drugzzz Flashcards
indications alpha blockers
- benign prostatic hyperplasia where lifestyle changes are insufficient. 5a-reductase inhibitors may be added
- add on rx in resistant HTN
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
adverse effects alpha blockers
postural hypotension
dizziness
syncope
particularly prominent after 1st dose
contraindications and cautions alpha blockers
should not be used in pts with existing postural hypotension
egs alpha blockers
doxazosin
tamsulosin
alfuzosin
antimuscarinics, what are the GU uses?
reduce urinary frequency, urgency and urge incontinence in overactive bladder if bladder training not effective
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
adverse effects antimuscarinics
dry mouth = common
tachycardia, constipation and blurred vision are also common
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
calcium and vit D uses in GU?
used in CKD to treat and prevent secondary hyperparathyroidism and renal osteodystrophy
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
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
calcium interactions
reduces absorption of many drugs incl iron, bisphosphonates, tetracyclines and levothyroxine
phosphodiesterase (type 5) inhibitors uses
erectile dysfunction
primary pulmonary htn
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
drug name for phosphodiesterase (type 5) inhibitors uses
sildenafil (viagra)
warnings sildenafil
do not use in pts whom vasodilation could be dangerous e.g recent stroke, ACS, cvd
SEs sildenafil
relate to action as vasodilator incl flushing, headache, dizziness and nasal congestion
serious: hypotension, tachycardia and palpitations
indications 5a-reductase inhibitors
benign prostatic hyperplasia, second line after a-blockers
e.g. 5a-reductase inhibitors
finasteride
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
