Lecture 9: Alpha blockers and Ca channel blockers Flashcards
What line of therapy are Ca channel and alpha blockers in hypertension?
Ca channel blocker is second line and Alpha blocker is third line
Describe the affinity of catecholamines for adrenergic receptors:
Alpha: Norepi>epi
Beta: Epi>norepi
Write some notes on adrenergic receptor distribution:
A1: Vasocon BV
B2: Vasodilate BV
B1: HR and contract
A1: Contractility
B2: Bronchi relaxation
A1: Kidney vasocon
B1 and B2: Renin release & seperately dec. Na tubular reabsorb.
What do alpha one (post synaptic) receptors do that we care about?
- Vasoconstriction (veins and arterioles) inc. BP
- A1A prostate….
- A1b Vascular smooth muscle
What do alpha two (post synaptic) receptors do that we care about?
- Inhibit noreepi and insulin release
What drug is an alpha 1 antagonist?
- Doxazosin (REVERSIBLE), prazosin
= Vasodilation, hypotension(
What are some alpha blocker indications?
- Hypertension
- Phaeochromocytoma (SNS tumor)
- Prostatism (inhibit SM)
Write some notes on doxazosin:
- Reversible alpha one blockade
- Blocks all a1 subtypes
- vasodilator
- oral drug
What are the possible side effects of alpha blockers?
- Orthostatic hypotension
- Lassitude
- Nasal stuffiness
- Dry mouth
- Urinary incontinence (Women)
What is a rarely used alpha blocker and why know about it?
Phenoxybenzamine
- Irreversible alpha blocker (both types)
- Used only for phaechromocytoma surgery as when its removed it causes a surge in catecholamines which could wake patient
Marked side effects
- Postural hypo, tachycardic
- Nasal stuffiness
What are some combined alpha and beta blockers and when are they used?
Labetalol
- Hypertension in pregnancy
Carvedilol
- Congestive HF
When is tamsulosin used?
- Prostatism
Less likely to cause orthostatic hypotension and has long half life
What are the indications to use Ca channel blocker?
Never a first line therapy
- Hypertension
- Angina (Dec. cardiac work, vasodilation)
- Arrhythmias (SVT termination, Afib rate control )
- Vasospasm
MoA of Ca channel blockers?
Block L-type Ca channels
- Cardiac and SM
Some selectivity
- Resistance vessels
- Myocardium
- Conducting tissues
Whats the impact of Ca channel blocker on vascular smooth muscle?
- Dec. arteriolar SM tone
- Dec. peripheral vascular resistance
- Decrease blood pressure and thus afterload
