1. © 2004 by Thomson Delmar Learning, a part of the Thomson Corporation. Fundamentals of Pharmacology for Veterinary Technicians Chapter 8 Cardiovascular Drugs

2. © 2004 by Thomson Delmar Learning, a part of the Thomson Corporation. Basic Anatomy and Physiology The functions of the cardiovascular system include delivery of oxygen, nutrients, and hormones to the various parts of the body The cardiovascular system also transports waste products to the appropriate waste removal system

3. © 2004 by Thomson Delmar Learning, a part of the Thomson Corporation. Basic Anatomy and Physiology

4. © 2004 by Thomson Delmar Learning, a part of the Thomson Corporation. Basic Anatomy and Physiology The electrical impulses of the heartbeat originate in the sinoatrial node (SA node) Heart rate is controlled primarily by the autonomic nervous system: –Stimulation of the parasympathetic nervous system slows heart rate –Stimulation of the sympathetic nervous system increases heart rate

5. © 2004 by Thomson Delmar Learning, a part of the Thomson Corporation. Basic Anatomy and Physiology Workload of the heart is divided into preload and afterload –Preload: volume of blood entering the right side of the heart –Afterload: force needed to push blood out of the ventricles If the heart is not working properly, it can compensate by a few mechanisms: –Increase heart rate –Increase stroke volume –Increase efficiency –Enlarge itself

6. © 2004 by Thomson Delmar Learning, a part of the Thomson Corporation. Cardiovascular Drugs Types of cardiovascular drugs –Positive inotropic drugs: increase the force of myocardial contraction –Negative inotropic drugs: decrease the force of myocardial contraction –Positive chronotropic drugs: increase heart rate by altering the rate of impulse formation at the SA node –Negative chronotropic drugs: decrease heart rate by altering the rate of impulse formation at the SA node –Positive dromotropic drugs: increase the conduction of electrical impulses –Negative dromotropic drugs: decrease the conduction of electrical impulses

7. © 2004 by Thomson Delmar Learning, a part of the Thomson Corporation. Cardiovascular Drugs Positive inotropes –Cardiac glycosides: Increase the strength of cardiac contractions, decrease heart rate, have an antiarrhythmic effect, and decrease signs of dyspnea Side effects include anorexia, vomiting, diarrhea, and cardiac arrhythmias Examples include digoxin and digitoxin –Catecholamines: Increase the force and rate of myocardial contraction, constrict peripheral blood vessels, and increase blood glucose levels Examples include epinephrine, dopamine, dobutamine, and isoproterenol

8. © 2004 by Thomson Delmar Learning, a part of the Thomson Corporation. Cardiovascular Drugs Antiarrhythmic drugs –Used to correct variation in the normal beating of the heart (which can lead to reduced cardiac output) –Types of antiarrhythmic drugs include local anesthetics, membrane stabilizers, beta- adrenergic blockers, action potential prolongation drugs, and calcium-channel blockers –Examples of antiarrhythmic drugs are listed in Table 8-3

9. © 2004 by Thomson Delmar Learning, a part of the Thomson Corporation. Cardiovascular Drugs Vasodilators –Drugs used to dilate arteries and/or veins, which alleviates vessel constriction and improves cardiac output –Examples include angiotensin- converting enzyme inhibitors, arteriole dilators, venodilators, and combined vasodilators

10. © 2004 by Thomson Delmar Learning, a part of the Thomson Corporation. Cardiovascular Drugs Diuretics –Drugs that increase the volume of urine excreted by the kidneys and thus promote the release of water from the tissues (lowers the fluid volume in tissue) –Used in the treatment of hypertension –Categories of diuretics include thiazides, loop diuretics, potassium-sparing diuretics, osmotics, and carbonic anhydrase inhibitors –Examples are listed in Table 8-4

11. © 2004 by Thomson Delmar Learning, a part of the Thomson Corporation. Cardiovascular Drugs Anticoagulants –Inhibit clot formation by inactivating one or more clotting factors –Used to inhibit clotting in catheters, to prevent blood samples from clotting, to preserve blood transfusions, and to treat emboli –Examples include heparin, EDTA, coumarin derivatives, aspirin, and blood transfusion anticoagulants

12. © 2004 by Thomson Delmar Learning, a part of the Thomson Corporation. Cardiovascular Drugs Hemostatic drugs –Help promote the clotting of blood –May be parenteral or topical –Parenteral Vitamin K 1 Protamine sulfate –Topical Silver nitrate, hemostat powder, gelfoam gelatin sponges, thrombogen topical thrombin solution

13. © 2004 by Thomson Delmar Learning, a part of the Thomson Corporation. Cardiovascular Drugs Blood-enhancing drugs –Affect RBCs –Affect the production or quality of RBCs –Examples: Iron Erythropoietin