Unit 4: drugs Flashcards
Describe clonidine
- centrally acting sympatholytic
- a2 receptor agonist that lowers bp by acting in brainstem vasomotor centers to supress sympathetic outflow to periphery
- will dec NE in the CNS which will dec SNS actiivity and inc PSNS activity
- treats high BP bc end result is that it decreases CO and dec PVR which will lower blood pressure
adverse effects of clonidine
light headedness, sedation and impaired concentration
how do Beta (β) blockers elicit antihypertensive effects
Beta (β) blockers or β-adrenergic antagonists have sympatholyic activity in the heart and kidney
- block the actions of catecholamines (ep in NE) at β1 receptors resulting in decreased blood pressure
- in heart they block β1 receptors decrease cardiac output
- block β1 receptors in the juxtaglomerular region of the kidney decrease renin release which decreases PVR.
*decreases CP and PVR = antihypertensive effect
ex: metoprolol an propranolol
compare metroprolol and propranolol
Both β-blockers
- propranolol is non-selective β-blockers does both β1 an β2
- metroprolol is β1 selective
*issues arise with patients with asthma because they also block β2 receptors in bronchioles
*drugs of choice for atrial arrhythmias
describe Prazoin
- peripherall acting sympatholytic
α1 blocker
- blockers the receptors in arteroils and neules
- DEC PVR and dilation of venus vessels
- dilation causes reduction in cardiac preload - praazoin has little tendency to inc CO and HR
- prescribed at vew low dose and titrated to higher doses depending on response
*perscribed for heart failure
- may cause water retention so diuretics and β-blockers might be administered in combination with α blockers.
describe sodium nitroprusside
- SNP
- vasodilator - nitric oxide donor
- causes vasodilation of arterial and venous vessels by acting activating guanylyl cyclase, therby increasing dephosphrylation of myosin light chains which result in relaxation of smooth muscle cells
- administered intravenously in cases of acute hypertensive emergency
- release CN ions which can be detoxified to avoid reaching toxic levels
- adverse effect = hypotension
describe verapamil
- vasodilator used in long-term treatment of hypertension
- Ca2+ channel blocker
– Ca2+ is involved in the electrical and mechanical events of the cardiac cycle and in vascular regulation
*Ca2+ activates myosin so it can bind to actin and cause muscle contraction
-SO dec Ca2+ will decrease contraction - blockers inhibit influex into arterial smooth muscle cells which causes them to relax resulting in vasodilation
*also dec Ca2+ levels in cardiac muscle cells
averse effects - associated w/ bradycardia
describe enalapril
- ACE inhibitor
- ester prodrug that is converted in the plasma to an active metabolite
- causes dec BP by the 4 ways in the pic
what is losartan
- angiotensin (AT1) receptor antagonist used to inhibit AT II actions
- effectiveness of AT1 blockers is simlar to ACE inhibitors
*dec BP
what is hydrocholrothiazide?
- thiazide diuretic used to treat mild to moderate hypertension
- acts on distal convoluted tubule to inhibit the sodium-chloride sympoter which results in water secretion into urine
- usually prescribed bc well absorbed orally, inexpensive and effective
- toxicities associated = hypokalemia, acute myocardial infraction, gout, and hyponatremia and are hazardous for patients with arrhythmias
what is furosemide
- loop diuretic which inhibits the co-transport of Na+, K+ and Cl- in the ascending loop of lendle
- elads to the inhibtion of NaCl reabsorption and excretion of water in urine
- used for more severe hypertension that requires a more poerful diuretic
- can be used alone or in combination with a sympatholytic or vasodilator
**rapid but short duration of action and toxicities are similar to those of thiazides (hypokalemia, acute myocardial infarction, gout, and hyponatremia)
in combination therapy for hypertension, that is typically the order that drugs are added to pateints treatment
- diuretics
- ACE inhibitors/ARB
- calcium channel blockers
- sympatholytics/vasodilators
descrieb digoxin
- cardiac glycoside
- treatment for patients with CHR and atrial fibrillation or englarged/dysfunctional left ventircle
- has direct and indriect pathway
- direct: acts on Na/K+ ATPase, increases intracellualr Ca2+ which increases interaction between actin and mysoin - inc cardiac contractility
- indirect: inc PSNS actiivty and dec SNS activity - inc force and decreased rate of contraction
*clearance is reduced by quinidine
what is quinidine
- anti- arrhythmic
- reduced clearance of digoxin - can increase its toxicity
what is nitroglycerin
- Vasodilator, a nitrate
- used to treat angina and CHF
- converts nirite -> nitrate -> NO this inc cGMP and causes relaxation of smooth muscle in blood vessels (vasodilation)
*decrease in venous return return and PVR and filation or coronary arteries
**requirement for oxygen decreases and delivery of oxygen increases
