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Cardio Pharmacology

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what is the formula for cardiac output?
stroke volume * heart rate
What are the three ways that a heart attempts to maintain or improve CO by increasing stroke volume?
increasing heart rate via increased sympathetics, increased sympathetic tone increasing inotropy of the myocardium, increase proload that results in increased CO
preload
the volume of blood in the ventricl at the end of diastole
afterload
the force that a ventricle must overcome while it contract during ejection
What are the three ways that myocardial oxygen demand varies directly with?
heart rate, myocardial wall tension, iontropic state
what is the target for loop diuretics?
sodium, potassium, and chloride reabsorption in the thick ascending loop of Henle
what is the mechanism of action of the loop diuretics?
bind to the Na, K, 2 Cl- symporter and prevent the binding and moving of ions into the cell
What is the percentage of water that can be filtered with the loop diuretics?
25%
is furosemide a high ceiling or low ceiling drug?
high ceiling
What is an awful place to put loop diuretics or any cardiac drug for that manner?
SQ or transdermally
when is the peak of diuretic activity of furosemide and what is its classification?
1 to 1.5 hours; loop diuretic
what are the side effects of loop diuretics in terms of electrolytes?
hyponatremia, hypochloremia, hypokalemia
What are three other loop diuretics along with furosemide?
Bumetanide, ethacrynic acid, torsemide
what is the target of the thiazide diuretics?
DCT sodium chloride symporter
what is the mechanism of action of thiazide diuretics?
inhibition of sodium reabsopriont within the DCT
What is the other common name that thiazide diuretics are called and why is it given this name?
calcium sparing diuretics; less calciuresis takes place with this drug
When you have a patient with ascites with right sided heart failure or biventricular failure what is the common drugs used?
loop diuretic in combination with thiazide diuretics
what are the kidney effects of cardiac thiazide diuretic drugs?
increased excretion of sodium, potassium ,and magnesium; overall increase in urine volume; significant loss of potassium (major side effect)
What are the two common thiazide diuretics?
hydrochlorothiazide and chlorothiazide
What is the main class of drug that interacts with thiazides?
NSAIDS
What is the most common potassium sparing diuretic?
spironolactone
What is the common misconception with potassium sparing diuretics?
diuretic ability (low)
what is the mechanism of action of potassium sparing diuretics?
works in the DCT and collecting ducts by antagonizing aldosterone effects.
Spironolactone
a drugs that is antimitogenic through aldosterone antagonism and is converted mainly by hepatic transformation to its active form canrenone
Why is reducing afterload important and what disease is it associated with mainly?
reducing afterload allows reduced cardiac work and increased stroke volume/cardiac output; This is used mainly with patients with mitral regurgitation (REGURG VOLUME CAN BE REDUCED AND WILL INCREASE FORWARD STROKE VOLUME AND REDUCE THE SIZE OF THE LEFT ATRIUM AND LEFT ATRIAL PRESSURE)
What are two examples of vasodilators?
alodipine and hydralazine
when is it warrented to absolutely not use vasodilators?
when the blood pressure is less than 70mm Hg
What is the main mechanism of action of alodipine
vasodilator; peripheral calcium channel blocker calcium induced calcium release is being stopped
What is the main effect of hydralazine
arterial vasodilator
venous vasodilators (preload or afterload)
generally are considered preload reducers
what is the main molecule in the body that is effected with venous vasodilators?
Nitric oxide
What is the proposed mechanism of action of venous vasodilators?
spontaneous release of NO activating smooth muscle guanylyl cyclase to form cGMP. cGMP inhibits calcium entry into the cell-->decreases intracellular calcium concentration cause smooth muscle relaxation; NO can also activate potassium channels leading to hyperpolarization and relaxation. NO acts through cGMP and can stimulate cGMP dependant protein kinase that activates myosin light chain phosphatase (dephosphorylates myosin light chains which leads to relaxation)
What are two vasodilators used in vet med?
nitroglycerin ointment (topical only); isosortbide dinitrate
classification of nitroprusside
mixed vasodilator
What are the storage conditions of nitroprusside
light sensitive, discard in 4 hours, place in normal saline
What is the classification of angiotensin converting enzyme inhibitors?
mixed vasodilators
What is the classification of bumetanide?
loop diuretic
what is the classification of ethacrynic
loop diuretic
what is the classification of torsemide?
loop diuretic
what is the mechanism of action of hydrochlorothiazide?
inhibition of the sodium chloride symporter on the distal convoluted tubule
What are the two major thiazide diuretics in veterinary medicine?
Hydrochlorothiazide and Chlorothiazide