Download Chapter 8 - Cardiovascular Drugs

Fundamentals of Pharmacology
for Veterinary Technicians
Chapter 8
Cardiovascular Drugs
© 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
© 2004 by Thomson Delmar Learning, a part of the Thomson Corporation.
Basic Anatomy and Physiology
© 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
© 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
© 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
© 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
© 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, betaadrenergic blockers, action potential
prolongation drugs, and calcium-channel
blockers
– Examples of antiarrhythmic drugs are listed in
Table 8-3
© 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 angiotensinconverting enzyme inhibitors, arteriole
dilators, venodilators, and combined
vasodilators
© 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
© 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
© 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 K1
• Protamine sulfate
– Topical
• Silver nitrate, hemostat powder, gelfoam
gelatin sponges, thrombogen topical
thrombin solution
© 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
© 2004 by Thomson Delmar Learning, a part of the Thomson Corporation.