Chapter 18 Agents that Dilate Blood Vessels
Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Coronary Vasodilators Used to treat coronary artery disease Coronary artery disease: inadequate delivery of blood, nutrients, and oxygen to the tissues
Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Chest Pain/Angina When the supply of oxygen and nutrients in the blood is insufficient to meet the demands of the heart, the heart muscle aches.
Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Vasodilator Drug Agents Three main objectives: Minimize frequency, duration, and intensity of episodes Offer few side effects Prevent myocardial infarction—death
Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Therapeutic Objectives Increase blood flow to ischemic heart muscle Decrease myocardial oxygen demand (continues)
Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Therapeutic Objectives Minimize the frequency of attacks Improve the client’s functional capacity Prevent or delay heart disease (continued)
Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Main Classes Acetylsalicylic acid (ASA) Nitrates Calcium channel blockers Beta blockers Angiotensin II receptor blockers
Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Nitrates Nitroglycerine Forms: sublingual, buccal, chewable, tablets, ointments, patches, spray, and intravenous
Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Nitroglycerine Causes central and peripheral vasodilation Relaxes smooth muscles Potent dilating effect on coronary arteries Used for prophylaxis and acute treatment of angina
Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Nitroglycerin Large first-pass effect when taken orally Transdermal—very effective IV form effectively used for: Hypertension Congestive heart failure Ischemic pain, myocardial infarction Pulmonary edema
Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Nitrates Example of long-acting nitrate Isosorbide dinitrate (Isordil) Provides: Acute relief of angina Long-term prophylaxis of angina
Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved General Side Effects Headache Diminish in intensity and frequency with use Tachycardia Postural hypotension Dermatitis Tolerance
Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Tolerance to Nitrates Long-acting form can become ineffective Solution Remove patch or cream at night for 8 hours Take the oral form for 16 hours a day
Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Interactions Additive hypotension with use of: Alcohol Beta blockers Calcium channel blockers Phenothiazines
Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Calcium Channel Blockers Reduces calcium ion influx: Reduction of myocardial oxygen consumption Coronary artery dilation Example: verapamil Side effects Dizziness, flushing, supraventricular arrhythmias
Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Beta-adrenergic Blocking Agents Block the beta receptors Reduce heart rate Reduce contractility Reduce blood pressure Example Atenolol Side effects Flushing, bradycardia, and bronchospasm
Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Peripheral Vasodilators Angiotensin II receptor blockers Block adrenergic receptors, or Direct action Interfere with epinephrine action Sympathetic nervous system is not stimulated Result: decreased blood pressure Side effects Orthostatic hypotension
Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved Aspirin Inhibits platelet clumping Given as a preventive agent Given when a person is experiencing a myocardial infarction