Pharm Exam 3: Anti-hypertensives 2/2 Flashcards
What are your different vasodilator drug classes used in htn?
- CCB
- direct arterial vasodilators
- nitrates
how do the drug class vasodilators aid in the tx of HTN?
relax arteriole smooth muscle –> decreased SVR.
are vasodilators a good single tx method for htn?
no d/t compensatory reflexes –> increased HR, blood volume, sodium
if you are using a vasodilator to tx htn, adding a beta blocker will stop what 3 compensatory mechanisms from counteracting the VD?
- block increased renin release
- block increase in HR
- block increased cardiac contractility
if you are using a vasodilator to tx htn, adding a diuretic will stop what compensatory mechanisms from counteracting the VD?
inhibit decreased renal sodium excretion (i.e. will increase sodium excretion, thus decreasing blood volume)
which vasodilator drugs cause direct arterial vasodilation through the opening of potassium channels
minoxidil and hydralazine
MOA of minoxidil
opens potassium channels in arterioles –> smooth muscle relaxation and vasodilation
MOA of hydralazine
- promote K efflux from vascular smooth muscle –> hyperpolarization and muscle relaxation
- arterial dilation by smM relax and increase in cGMP
hydralazine dilates ________________ not ________ or _____________
arterioles; veins; epicardial arteries
s/e of hydralazine
- HA
- n/v
- flushing
- peripheral neuropathy
use of _______________ for tx of htn has a risk of tachyphylaxis
hydralazine
how much of hydralazine is bioavailable after first pass?
25%
why is hydralazine not a good choice of anti-htn, especially in the OR
- variable responses d/t acetylation
- 10-20 min onset
- reflex tachycardia, contractility, and activation of RAAS
what are the functions of NO
- relax vascular smM
- inhibit plt aggregation
- inhibit leukocyte-endothelial interactions
__________________ is a direct acting nitrodialator
sodium nitroprusside
what is the difference in a direct acting and indirect acting nitrodilator
direct - releases NO spontaneously; indirect must be nitrogenated (i.e. activated) before releases NO
in the smooth muscle, indirect acting nitrodilators are denitrogenated by ___________________
glutathion s-transferase
in the mitochondria, indirect nitrodilators are denitrogenated by ________________
aldehyde dehydrogenase
isosorbide dinitrate and mononitrate are the oral formulary for which medication?
nitroglycerine
what is an example of an indirect acting nitrodilator
nitroglycerine
nitroglycerine, at high concentrations _______________ responds, but at low concentrations ________________ responds
arteries; veins
what is the main clinical use of nitroglycerine
Angina
primary effects of nitroglycerine
- venous relaxation
- increased venous capacity
- decreased preload and pulmonary pressure
- Dilates epicardial coronary arteries
- Reduces myocardial O2 demand (by reducing PL)
- decreased heart size
what are the adverse effects of nitroglycerine
- orthostatic hypotension
- syncope
- throbbing headache
what are some secondary effects of nitroglycerine
- reflex tachycardia and contractility d/t baroreceptor response
- decreased plt aggregation
- Risk for tachyphylaxis
how does adenosine fx as a nitrodilator
- activates purinergic receptors on endothelial cells to stimulate release of NO - VD on smM
- blocks calcium entry at phase I of action potential - inhibiting contraction
effects of nitroprusside
- dilates arteries and veins
- increases cGMP –> relaxing of vascular smM
what are the byproducts of nitroprusside metabolism
cyanide + NO
Where is nitroprusside metabolized?
RBC
how do you treat cyanide toxicity from nitroprusside
- stop NTP
- give Sodium thiosulfate
- 100% FiO2
- can also give methylene blue for the methmyoglobin
T/F: adults are normally able to detoxify cyanide formed from sodium nitroprusside
True
when is cyanide toxicity with sodium nitroprusside risk increased?
- large prolonged dosing
- hepatic dz
- renal dz
what are some signs of cyanide toxicity
- hypertension
- metabolic acidosis
- lactate > 8
- CV collapse
Late signs: - hypotension
- seizure/coma death
- elevated SvO2
signs and sx of cyanide toxicity is often is preceded by ________________
tachyphylaxis
Calcium channel blockers as anti-htn cause __________________, through blockage of _______________ channels in smooth muscle of vessels
arterial dilation; L-type Ca channels