PBL Drug Mechanism and Class

Question 1

What are the three mainstay treatments for prolonging the life of a patient with heart failure?

Answer 1

1. Aldosterone Receptor Blockers (Spirononlactone)
2. ACE Inhibitors (Lisinopril)
3. Beta-blockers

Question 2

What are diuretics and other drugs used for in heart failure?

Answer 2

Symptom management

Question 3

What do you use to treat HF acutely?

Answer 3

• Diuretics (to remove fluid)
• Nitroglycerin (venodilation)
• NO beta blockers – they will further reduce SV (negative inotrope)

Question 4

What do you use to treat HF long term?

Answer 4

Try to get rid of compensatory mechanisms:

• ACE inhbitor is ideal long-term
• Angiotensin-receptor blockade “ARBs” could be helpful
• Beta blockers should be used for chronic Tx ONLY!!

Question 5

Mechanism of Nitric Oxide/Nitroglycerin:

Answer 5

• Vasodilator of VEINS!
• Relaxes smooth muscle via inc. in cGMP –> causes decrease in intracellular Ca2+ –> less smooth muscle contraction
• When inhaled, it can work as a bronchodilator:
• Can also inc. PaO2 (partial pressure of oxygen in blood) by dilating pulmonary vessels in better ventilated areas of the lung, which then redistributes blood AWAY from regions of poor game exchange TOWARDS regions of better gas exchange
• Shorter t1/2 (this is why you need a nitro drip after tabs)

Question 6

What class is Nitroglycerin?

Answer 6

Nitrates/Nitrites

Question 7

What class is Isosorbide dinitrate?

Answer 7

Nitrate/Nitrite

Question 8

Mechanism of Isosorbide dinitrate?

Answer 8

• Venodilator, similar to nitro
• Much longer t1/2 than nitro (1-1.5 hours)
• Stimulates cGMP production, resulting in vascular smooth muscle relaxation. Peripheral VENOUS resistance dec. via selective action on VENOUS capacitance vessels –> venous pooling of blood AND dec. venous return to the heart
• Results in dec. preload (venous filling) and dec. afterload
• Venous dilation is greater than arterial bc the enzyme that converts it to NO is more abundant in venous cells than in arterial cells

Question 9

What drug class is Furosemide?

Answer 9

Loop diuretic

Question 10

What is the mechanism of furosemide?

Answer 10

Inhibits NKCC2, the luminal Na+-K+-2CL- symporter in the thick ascending limb of the loop of henle. This increases the excretion of Na+ and Cl- (water follows the ions) = less fluid in body.

Question 11

What is the ending of ACE inhibitors?

Answer 11

Angiotensin Converting Enzyme Inhibitors

-pril

Question 12

What are two ACE inhibitors we should know?

Answer 12

Enalapril

Lisinopril

Question 13

What is the mechanism of Enalapril?

Answer 13

Suppresses the renin-angiotensin-aldosterone system. It is an ACE inhibitor –> can’t convert Angiotensin I to Angiotensin II –> thus no aldosterone
-Used in management of symptomatic heart failure

Question 14

What drug class is Metoprolol?

Answer 14

Beta1 selective adrenergic blocking agent

Question 15

What is the ending of Beta blockers? What two beta blockers should you know?

Answer 15

-olol
Metoprolol
Propanolol

Question 16

What is the mechanism for beta blockers?

Answer 16

Inhibits response to adrenergic stimuli by competitively blocking beta1-adrenergic receptors within the myocardium.

• Blocks beta2 adrenergic receptors within bronchial and vascular smooth muscle only in high doses
• Dec. resting HR, reflex orthostatic tachycardia, myocardial contractility, and CO.
• Management of mild to moderately severe (NYHA class II or III) heart failure of ischemic, hypertensive or cardiomyopathic origin (along with ACE inhib., diuretics, and cardiac glycosides)

Question 17

What is the drug class of Eplerenone?

Answer 17

Antimineralocorticoid

Question 18

What two antimineralocorticoids must you know?

Answer 18

Eplerenone

Spirinolactone

Question 19

What is the mechanism of Eplerenone?

Answer 19

Antagonist of the mineralcorticoid aldosterone receptor. It works by blocking the action of aldosterone.

• Produces sustained increases in plasma renin and serum aldosterone concentrations, reflecting the inhibition of the negative feedback of aldosterone on renin secretion.
• Recommended with select patients with NYHA class II-IV heart failure and left ventricular ejection fraction = 35% to reduce morbidity and mortality.

Question 20

What drug class does digoxin belong to?

Answer 20

Cardiac glycosides

-Cardiotonic agents

Question 21

What is the mechanism of digoxin?

Answer 21

Inhibits activity of Na+-K+-ATPase, an enzyme required for active transport of sodium out of myocardial cells.
-This leads to higher increase of sodium inside the cell –> sodium/calcium antiproton present on myocardial cell membrane –> less Ca2+ can be transported out of myocardial cells –> excess Ca2+ stored in SR –> Ca2+ needed for contraction.
–Main property: Ability to inc. force and velocity of myocardial systolic contraction (positive inotropic action) by a direct action on the myocardium
(+) inotrope
(-) chromotrope

Question 22

What class does Acetazolomide belong to?

Answer 22

Carbonic Anhydrase Inhibitor

Question 23

What does Acetazolamide do?

Answer 23

Blocks carbonic anhydrase.

-Dec. fluid reabsorption and CO.

Question 24

What class does Hydralazine belong to?

Answer 24

Direct vasodilators

Question 25

What is the mechanism of Hydralazine?

Answer 25

Arterial vasodilator
-Has a direct vasodilatory effect on vascular smooth muscle.
“Unclarified mechanism”