Cardiovascular Drugs 1 Flashcards
(29 cards)
Cardiovascular System
- Comprised of heart and blood vessels
- Its main function is to transport to and from body tissues
- Drugs used to treat the CV system are potent and can have serious side effects
Normal cardiac cycle
o Atria contract pushing blood into ventricles
o Ventricles contract pushing blood out to body tissues
Cardiac muscle contraction is controlled by:
• is controlled by the movement of mineral ions in and out of cardiac muscle cells
o movement of ions across cell membrane leads to depolarization
o depolarization of cardiac muscle cells causes contraction
o waves of depolarization always begin at the sinoatrial (SA) node, then progressively spread
waves of depolarization always begin at the sinoatrial (SA) node, then progressively spread to
atria
atrioventricular (AV) node
Bundle of Hiss
ventricles
Effect of autonomic nervous system on CV function
Sympathetic n.s.-> inc. HR and contractility
-> vasoconstriction
Parasympathetic n.s.-> dec. HR
Arrhythmia
an abnormal pattern of electrical activity in the heart
Antiarrhythmic Drugs
- Usually caused by a group of abnormal cells -> depolarize on their own, not in conjunction w/ the SA node
- Antiarrhythmics prevent autodepolarization of these cells by slowing down the movement of ions through their cell membranes
Sodium influx inhibitors
• lidocaine, quinidine, procainamide
o inhibit movement of sodium ions across cell membranes
Licocaine
should be given IV
large doses may cause sedation, ataxia, drowsiness
cardiovascular shock and seizures occur w/ overdose
Procainamide and quinidine
- both available in oral form
- procainamide can be given IM, IV
- quinidine can
- -cause vomiting, diarrhea, anorexia
- -increase digoxin plasma levels
Calcium channel blockers
diltiazem, verapamil
- block movement of calcium across channels in the cell membrane
- may decrease heart contractility
Beta blockers
propanolol
-blocks sympathetic n.s. receptors, dec. contraction rate of the heart
Adverse effects of Beta blockers
decreases contractility
bronconstriction
abnormally slow HR
lose effectiveness over time
Positive Inotropic Drugs
- Increase the strength of contraction of the heart
* Used when heart muscle is too weak to pump (e.g. congestive hear failure)
Pimobendan
o Newest inotropic drug that is also a vasodilator
o Increases intracellular calcium sensitivity
o Used to treat CHF due to dilated cardiomyopathy or valve insufficiency
o Can be safely used in conjunction with other cardiac drugs
Digoxin
-Older inotropic drug
-makes more calcium available inside cardiac muscle cells to improve contraction
-enhances the parasympathetic n.s. effect on the heart
-narrow therapeutic range
(Adverse effects include anorexia, vomiting, diarrhea, arrhythmia)
Vasodilators
o Vasoconstriction is the body’s response to low blood pressure due to a failing heart
Makes it harder for the failing heart to pump blood
o Vasodilators prevent vasoconstriction from occurring
Enalapril (Enacard), Benazepril, Captopril
block formation of angiotensin II which is responsible for vasoconstriction and sodium retention
Hydralazine
causes direct relaxation of vascular smooth muscle
Prazosin
blocks vasoconstriction caused by the sympathetic n.s.
Nitroglycerin
applied topically, caused dilation of veins
Diuretics
- Increase urine formation to promote water loss from the body
- decreases the volume of blood the heart has to pump
Furosemide (Lasix)
- prevents reabsorption of sodium from the renal tubule
- prolonged use can lead to abnormally low potassium levels
Thiazide diuretics (chlorthiazide
- prevents reabsorption of sodium from the renal tubule
- prolonged use can lead to abnormally low potassium levels
- less potent than furosemide
- loses effectiveness w/ long-term use
