Agents that Dilate Coronary Blood Vessels

 Coronary artery disease (CAD) results from atherosclerosis  Clinical symptoms caused by  narrowing of the vessels  inadequate delivery of blood, nutrients, and oxygen  Localized muscle injury  Increased lactic acid

 Pain produced (angina pectoris)  When the supply of oxygen and nutrients in the blood is insufficient to meet the demands of the heart, the muscle aches  Aggravated with stress or exercise  Drugs treat by dilating coronary blood vessels

 Angina pectoris : chest pain  affects ~ 9.8 million Americans/year  More prevalent in older men  The more vessels involved, the poorer the prognosis

 Used to treat coronary artery disease  Coronary artery disease: inadequate delivery of blood, nutrients, and oxygen to the tissues

 Three main objectives: ◦ Minimize frequency, duration, and intensity of episodes ◦ Offer few side effects ◦ Prevent myocardial infarction—death

 Increase blood flow to ischemic heart muscle  Decrease myocardial oxygen demand

 Minimize the frequency of attacks  Improve the client’s functional capacity  Prevent or delay heart disease

 Acetylsalicylic acid (ASA)  Nitrates  Calcium channel blockers  Beta blockers  Angiotensin II receptor blockers

 Nitroglycerine ◦ Forms: sublingual, buccal, chewable, tablets, ointments, patches, spray, and intravenous

 Causes central and peripheral vasodilatation ◦ Relaxes smooth muscles  Potent dilating effect on coronary arteries  Used for prophylaxis and acute treatment of angina

 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

 Do not leave the patient when he or she is changing positions after starting a new prescription for nitro ◦ Nitroglycerin is intended to cause rapid vasodilation -> dizziness with position change ◦ Nitro paste: remove med from patient’s skin and wash/dry before reapplying ◦ Always wear gloves when applying nitro topically

 Example of long-acting nitrate ◦ Isosorbide dinitrate (Isordil)  Provides: ◦ Acute relief of angina ◦ Long-term prophylaxis of angina

Headache  Diminish in intensity and frequency with use Tachycardia Postural hypotension Dermatitis Tolerance

 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

 Additive hypotension with use of: ◦ Alcohol ◦ Beta blockers ◦ Calcium channel blockers ◦ Phenothiazines

 Reduces calcium ion influx: ◦ Reduction of myocardial oxygen consumption ◦ Coronary artery dilation  Example: Verapamil  Side effects ◦ Dizziness, flushing, supraventricular arrhythmias

 Block the beta receptors ◦ Reduce heart rate ◦ Reduce contractility ◦ Reduce blood pressure  Example ◦ Atenolol  Side effects ◦ Flushing, bradycardia, and bronchospasm

 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

 Inhibits platelet clumping ◦ Given as a preventive agent ◦ Given when a person is experiencing a myocardial infarction

 Patients should carry ID  Teach smoking/tobacco cessation, med use  Assess angina attacks  Teach: nitroglycerine (NTG) most effective when taken at the beginning of an angina episode

 Teach: replace sublingual NTG Q 3 months  IV NTG requires special preparation: glass, not plastic  Give beta-blocking agents before vasodilators  Monitor blood pressure routinely