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Antianginal Agents. Dr.Shadi-Sarahroodi Pharm.D & PhD Qom University of Medical sciences Iran PUBLISHED BY www.medicalppt.blogspot.com. Angina Pectoris (Chest Pain).
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Antianginal Agents Dr.Shadi-Sarahroodi Pharm.D & PhD Qom University of Medical sciences Iran PUBLISHED BY www.medicalppt.blogspot.com www.medicalppt.blogspot.com for more lecture notes
Angina Pectoris (Chest Pain) • When the supply of oxygen and nutrients in the blood is insufficient to meet the demands of the heart, the heart muscle aches. www.medicalppt.blogspot.com for more lecture notes
Types of Angina • Atherosclerotic angina (also called classic or effort angina) • Vasospastic angina(also called Prinzmetal’s or variant angina) • Unstable angina(also called preinfarction or crescendo angina) www.medicalppt.blogspot.com for more lecture notes
Antianginal Agents: Therapeutic Objectives • Increase blood flow to ischemic heart muscle and/or • Decrease myocardial oxygen demand www.medicalppt.blogspot.com for more lecture notes
Antianginal Agents • Nitrates • Beta blockers • Calcium channel blockers www.medicalppt.blogspot.com for more lecture notes
intracellular conversion to nitrite ions, and then to nitric oxide • activates guanylatecyclaseand increases the cells' cyclic guanosinemonophosphate(cGMP). • Elevated cGMP ultimately leads to dephosphorylation of the myosin light chain, resulting in vascular smooth muscle relaxation www.medicalppt.blogspot.com for more lecture notes
Organic Nitrates Ferid Murad www.medicalppt.blogspot.com for more lecture notes
Antianginal Agents: Nitrates Available forms: Sublingual Ointments Buccal Transdermal patches Chewable tablets Inhalable sprays Capsules Intravenous solutions www.medicalppt.blogspot.com for more lecture notes
BENEFITS OF NITRATES • Reduce myocardial oxygen demand by dilating veins and increase venous pooling of blood • Increase systemic arteriolar vasodilation (intravenous forms only) • Directly dilate undiseased coronary arteries, helping restore blood flow deep within myocardial tissues • Decrease ventricular wall tension due to increased venous pooling • Improve exercise tolerance www.medicalppt.blogspot.com for more lecture notes
Antianginal Agents: Nitrates Nitroglycerin • Prototypical nitrate • Large first-pass effect with PO forms • Used for symptomatic treatment of ischemic heart conditions (angina) • IV form used for BP control in perioperative hypertension, treatment of CHF, ischemic pain, and pulmonary edema associated with acute MI www.medicalppt.blogspot.com for more lecture notes
Antianginal Agents: Nitrates • isosorbide dinitrate (Isordil, Sorbitrate, Dilatrate SR) • isosorbide mononitrate (Imdur, Monoket, ISMO) Used for: • Acute relief of angina • Prophylaxis in situations that may provoke angina • Long-term prophylaxis of angina www.medicalppt.blogspot.com for more lecture notes
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Antianginal Agents: Nitrates Side Effects • Headache • Usually diminish in intensity and frequency with continued use • Tachycardia, postural hypotension • Tolerance may develop • facial flushing, and tachycardia www.medicalppt.blogspot.com for more lecture notes
Tolerance • blood vessels become desensitized to vasodilation • daily “nitrate-free interval” • typically 10 to 12 hours, usually at night, because demand on the heart is decreased at that time • variant angina worsens early in the morning, perhaps due to circadian catecholamine surges www.medicalppt.blogspot.com for more lecture notes
Antianginal Agents: Beta Blockers www.medicalppt.blogspot.com for more lecture notes
Antianginal Agents: Beta Blockers Mechanism of Action • Decrease the HR, resulting in decreased myocardial oxygen demand and increased oxygen delivery to the heart • Decrease myocardial contractility, helping to conserve energy or decrease demand www.medicalppt.blogspot.com for more lecture notes
Propranolol is the prototype: not cardioselective • metoprolol or atenolol, are preferred www.medicalppt.blogspot.com for more lecture notes
All β-blockers are nonselective at high doses and can inhibit β2 receptors. • Important in asthmatics. www.medicalppt.blogspot.com for more lecture notes
contraindication • Asthma • Diabetes • severe bradycardia • peripheral vascular disease • chronic obstructive pulmonary disease. www.medicalppt.blogspot.com for more lecture notes
Do not discontinue β-blocker therapy abruptly. • The dose should be gradually tapered off over 5 to 10 days to avoid rebound angina or hypertension.] www.medicalppt.blogspot.com for more lecture notes
Antianginal Agents: Calcium Channel Blockers www.medicalppt.blogspot.com for more lecture notes
Mechanism of Action • Calcium influx is increased in ischemia because of the membrane depolarization that hypoxia produces • In turn, this promotes the activity of several adenosine triphosphate–consuming enzymes, thereby depleting energy stores and worsening the ischemia www.medicalppt.blogspot.com for more lecture notes
Antianginal Agents: Calcium Channel Blockers • Cause peripheral arterial vasodilation • Reduce myocardial contractility (negative inotropic action) • Result: decreased myocardial oxygen demand www.medicalppt.blogspot.com for more lecture notes
Nifedipine • a dihydropyridine derivative • arteriolar vasodilator • Oral • Usually: extended-release tablets. • Hepatic metabolism • Eliminate in both urine and the feces www.medicalppt.blogspot.com for more lecture notes
Side Effects • Flushing • Headache • Hypotension • peripheral edema as • all calcium-channel blockers are with constipation is a problem www.medicalppt.blogspot.com for more lecture notes
Verapamil • Slows AV conduction • decreases heart rate, contractility, blood pressure, and oxygen demand • contraindicated in patients with preexisting depressed cardiac function or AV conduction abnormalities www.medicalppt.blogspot.com for more lecture notes
Diltiazem • slow AV conduction • decrease the rate of firing of the sinus node pacemaker • metabolized by the liver www.medicalppt.blogspot.com for more lecture notes
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