Antihypertensives Flashcards
Define BP
The force/tension of blood pressing against arterial walls
What is the equation for BP?
CO x SVR
What is essential HTN?
no identifiable cause, likely d/t environment and genetics. 95% of cases.
What is secondary HTN?
CKD, Cushings, pheos, OSA
What are the limits for Stage 1 HTN?
130/80
What are the limits for Stage 2 HTN?
140+/90+
What constitutes HTN crisis?
180+/120+
What regulates BP?
Pressure sensitive neurons called baroreceptors in the aortic arch and carotid sinuses–they form the vagus nerve at the aortic arch
Explain mechanism of BP regulation.
If BP falls too low baroreceptors send signals to adrenal medulla causing release of catecholamines and increasing sympathetic activity through activation of beta and alpha receptors.
What do beta 1 receptors do?
increase HR and SV, thus increasing CO and BP
What do alpha 1 receptors do?
on smooth muscles, vasoconstrict, increasing vascular resistance and increasing BP
What are the classifications of antihypertensives?
sympatholytics, calcium channel blockers, angiotensin converting enzyme inhibitors, angiotensin II receptor inhibitors, centrally acting drugs, diuretics
What’s another name for sympatholytics?
adrenergic antagonists
What do sympatholytics do?
inhibit activity of SNS mediated by epi/NE, bind to adrenergic receptors of smooth muscle causing vasodilation and decreased SVR, prevent their activations.
What are the groups of sympatholytics?
alpha blocker and beta blocker
What are examples of non-selective alpha blockers?
phentolamine, phenoxybenzamine
How can non-selective alpha blockers cause tachycardia and arrhythmias?
non-selective bind to alpha-1 and 2, NE acts on alpha-2 so blocking this results in more NE release which can then stimulate beta-1 receptors on the heart
What’s the difference between phentolamine and phenoxybenzamine?
phentolamine is reversible, phenoxybenzamine is not.
What do alpha-1 antagonists end in? examples?
-osin, prazosin, terazosin, doxazosin, alfuzosin, tamulosin
How do alpha-1 antagonists work?
selectively and reversibly block alpha-1 receptors from vascular smooth muscle which reduces PVR and BP
Is there still baroreceptor involvement with alpha-1 antagonists?
yes, cause hypotension and tachycardia
Do alpha-1 antagonists have more or less side effects that non-selective alpha blockers?
less, since negative feedback inhibition through alpha-2 receptors is still working
What’s different about the alpha-1 antagonists: alfuzosin, silodosin, and tamulosin?
little effect on BP but more so for relieving enlarged prostate, increased activity of alpha-1 receptors in prostate, less alpha-1 in blood vessels.
What are side effects of alpha-1 antagonists?
orthostatic hypotension, headaches, nasal congestion, reflex tachy unlikely because selective antagonist doesn’t impact NE regulating effect of alpha-2 receptor