13: Alpha blockers and Ca channel blockers Flashcards
Which subtype of alpha receptor is located on the prostate?
Alpha1b
Which alpha blocker is alpha 1a specific?
Tamsulosin
Alpha blockers are ___ line therapy for hypertension alongside ___ and ____
Third line
ACEi and diuretic
What is a phaeochromocytoma? How is this managed perioperatively?
- Tumour of the SNS
- Given phenoxybenazmine perioperatively to reduce surge in NE
Which drug is most helpful in hypertensive men with prostate symptoms?
Doxazosin
What are teh side effects of alpha blockers?
- Orthostatic hypotension
- Lassitude (tiredness)
- Nasal stuffiness
- Dry mouth
- Urinary incontinence
Why are the side effects of phenoxymenzamine so pronounced?
- Irreversible alpha blocker (a1 > a2)
- Antihistamine, anticholinergic, blocks serotonin receptors
What advice would you give someone on an alpha blocker?
- Stand up slowly
- Take first dose at night time
What are the indications for Ca channel blockers?
- Hypertension
- Angina
- Arrhythmias
- Vasospasm
What is the role of Ca channel blockers in arrhythmias?
Slow down heart rate but are NOT anti arrhythmic
What are the 3 classes of Ca channel blockers and examples of each?
- Dihydropyridine - nifedipine, felodipine, amlodipine
- Benzothiazepine - diltiazem
- Phenylalkylamine - verapamil
How are Ca channel blockers usually prepared?
All oral, IV of diltiazem and verapamil
What are the side effects of:
- Dihydropiridines?
- Phenylalylkamines?
- Nifedipine: flushing, headache, oedema
- Verapamil: heart block, -ve inotrope, constipation
Diltiazem/verapamil can be used with beta blockers
Diltiazem (slow down HR in AF)
What are some important drug interactions of verapamil?
- Inhibits CYP450 (statins)
- Inhibits PGP (digoxin, cyclosporin)
