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Part 6 Antianginal Drugs 抗心绞痛药. Organic nitrates receptor blockers Calcium channel blockers. 1. OVERVIEW. Coronary vessels: blood supply for the heart. Coronary atherosclerosis: cause of cardiac ischemia. Distribution of coronary arteries in the heart.
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Part 6Antianginal Drugs抗心绞痛药 Organic nitrates receptor blockers Calcium channel blockers
1. OVERVIEW Coronary vessels:blood supply for the heart
Coronary atherosclerosis: cause of cardiac ischemia
Ischemia (angina pectoris): 心绞痛:心肌氧供需不平衡 imbalance between oxygen demand and supply
1. OVERVIEW Classification of angina pectoris 心绞痛类型: Exertional angina (劳累性心绞痛) Stable angina (稳定性心绞痛) Initial onset angina (初发型心绞痛) Accelerated angina (恶化性心绞痛) Spontaneous angina (自发性心绞痛) Angina decubitus (卧位型心绞痛) Variant [or vasospastic] angina (变异性[痉挛性]心绞痛) Acute coronary insufficiency (急性冠脉功能不全) Postinfarction angina (梗死后心绞痛) Mixed angina (混合性心绞痛) Unstable angina(不稳定性心绞痛): link of stable angina and myocardial infarction
1. OVERVIEW Myocardial oxygen demand is chiefly determined by: • 心肌耗氧量因素: • Contractility 收缩力 • Heart rate心率 • Wall tension 室壁张力 • Preload (venous return ) • 前负荷(静脉回流量) • Afterload (arteriolar resistance) • 后负荷(动脉阻力) afterload preload
1. OVERVIEW Myocardial oxygen demand is diminishedby: 降低心肌耗氧量: • Reducing contractility 收缩力 • Reducing heart rate 心率 • Reducing the preload 前负荷 • Reducing the afterload 后负荷 Wall tension 室壁张力
1. OVERVIEW • Myocardial oxygen supply is chiefly determined by: • 心肌供氧量: • AV oxygen difference 氧分压 • Regional myocardial distribution局部血流分布 • coronary blood flow: • vascular resistance, artery pressure • 血管阻力,动脉压
1. OVERVIEW Effects of antianginal drugs 抗心绞痛药作用: Reducing oxygen demands 降低心肌耗氧量 Reducing heart rate and contractility Dilating systemic arteries and veins ( wall tension by lowering heart loads) Increasing oxygen supply 增加供血供氧 Dilating conduct coronary arteries ( coronary blood flow) Promoting regional distribution ( in ischemic regions) Others 其他: Anti-platelet coagulation and thrombus formation
2. Antianginal drugs 2.1 Nitrates Nitroglycerin(硝酸甘油) A. Pharmacological actions 药理作用 Dilating vessels and reducing heart loads wall tension ; reflex tachycardia Redistribution of coronary circulation dilating conduct artery: collateral circulation reducing wall tension: blood flow in ischemic subendocardial area
2. Antianginal drugs Influence of organic nitrates and dipyridamole on the blood supply of ischemic area
2. Antianginal drugs B. Clinical uses 临床应用 • Angina pectoris: all kinds, especially stable type • Heart failure:reducing heart loads due to vasodilation C. Adverse reactions 不良反应 • Increase in heart rate and contractility 心率、收缩力 • Symptoms due to vasodilation血管扩张引起:headache, flash, postural hypotension, collapse, ect. • Others: methaemoglobinaemia(高铁血红蛋白) • Tolerance 耐受性: avoiding steady-state plasma concentration; • supplement of agents containing –SH (captopril)
2. Antianginal drugs 2.1 Other nitrates 其他硝酸酯类 Isosorbide dinitrate (硝酸异山梨酯) Isosorbide-5-mononirate (5-硝酸异山梨酯) Compared with nitroglycerin 与硝酸甘油比较的特点: • Orally active 口服有效 • Similar but weaker effect 作用相似但较弱 • Acting slowly but lasting longer 作用缓慢、持久 • Larger individual variation and more adverse effects • 个体差异大,不良反应多见
2. Antianginal drugs 2.2 receptor blockers 受体阻断药 A. Pharmacological action 药理作用 • Reducing oxygen demand: • heart rate and contractility • Increasing oxygen supply: • diastolic period : perfusion time • vascular tone in normal regions : • blood flow in ischemic regions • Others: • Improving myocardial metabolism • Inhibiting coagulation of platelets
2. Antianginal drugs B. Clinical uses 临床应用 stable and unstablepectoris, especially associated with hypertension or arrhythmias, even with myocardial infarction; but not used forvariant angina pectoris C. Notes 注意点 • Dose individualization: starting from small dose • Withdraw gradually and slowly: symptomrebound • Combination with nitroglycerin but without verapamil • Contraindicated in heart depression, asthma, and so on
2. Antianginal drugs 2.3 Calcium channel blockers 钙拮抗剂
2. Antianginal drugs 2.3 Calcium channel blockers A. Pharmacological actions 药理作用 • Reducing myocardial oxygen remand: • heart loads : nifedipine • heart rate and contractility:verapamil and diltiazem • Increasing myocardial blood supply • Protecting ischemic myocardial cells • Inhibiting coagulation of platelets
Selective calcium channel blockers • Dihydropyridines (二氢吡啶类): • nifedipine 硝苯地平 rapid, hypotension, reflex tachycardia • amlodipine 氨氯地平 high bioavailability, t1/2 40-50 h, long-acting, less influences on heart rate and blood pressure • Phenylalkylamines (苯烷胺类): • verapamil 维拉帕米 reducing oxygen demands, antiarrhythmia • Benzothiazepines (苯硫卓类): • diltiazem 地尔硫卓 weaker for heart depression and vasodilation;suitable for variant angina pectoris 艹 艹
2. Antianginal drugs B. Clinical uses 临床应用 stable and variant type: nifedipine, verapamil, diltiazem unstable type: verapamil, diltiazem Actions of DHP (like nifedipine) are similar to those of nitroglycerin Actions of verapamil are similar to those of blockers Actions of diltiazemare intermedial in both above drugs
3. Summary of antianginal drugs nitroglycerin blockers Ca2+ antagonistscombination* Heart rate Contractility / Wall tension / / Oxygen demand Blood pressure : increase, : markedly increase; : decrease, : markedly decrease; : variable according to the dose and effect of each drug ; * blockerscombined with nitroglycerin or Ca2+ antagonists (nifedipine; combination with verapamil/diltiazem not be recommendated) Caution:Combination may potentiate the antianginal effects, but may induce severe hypotension
2. Antianginal drugs 2.4 Other drugs 其他药物 ACEIs (血管紧张素转化酶抑制药) • Treating hypertension and preventing ischemic heart disease • Reducing heart loads • Inhibiting cardiac remodeling Nicorandil (尼可地尔) • Opening ATP-sensitive K+ channel (KATP) • Lowering intracellular Ca2+ • Providing NO (like nitroglycerin) • Inducing ischemic preconditioning
2. Antianginal drugs Molsidomine (吗多明) • Promoting collateral circulation • Similar to nitroglycerin • Used in stable angina Dipyridamole (双嘧达莫,潘生丁) • Inhibiting adenosine uptake and cAMP degradation • Inhibiting pletelet aggregation • Small doses, long-term oral administration
Cardiovascular pharmacology Summary
Overview of Cardiovascular Diseases • Common Cardiac Diseases • Abnormal contractility:Heart failures • Abnormal rhythms:Arrhythmias • Abnormal blood supply:Ischemic heart diseases • Myocardial disorders • Common vascular diseases • Abnormal systematic resistance:Hypertension • Dysfunction of coronary vessels:Coronary vascular diseases • Dysfunction of cerebral vessels:Cerebral ischemia, hemorrhage • Dysfunction of pulmonary vessels:Pulmonary hypertension • Dysfunction of peripheral vessels: Peripheral vascular disorder • Arteriosclerosis: basis of most CVS diseases
Overview of Cardiovascular Drugs • Classification based on target organs/tissues • Heart:Heart failures, arrhythmias, cardiac ischemia • Vessels:Vasodilatation, vasoconstriction, arteriosclerosis • Classification based on the mechanisms • Ion channels:Ca2+, Na+, K+ channels • Receptors:Adrenoceptors, AT1 receptors, etc. • Enzymes:ACEI, Na+-K+-ATPase, HMG-CoA reductase • Others:Diuretics
Cardiovascular Drugs • Antiarrhthemic drugs • Classification; Typical drugs and their properties • Antihypertensive drugs • Classification; Properties of 6 main drug classes • Drugs for treating heart failure • Classification; ACEIs, blockers, cardiac glycoide • Antiatheroscleotic drugs • HMG CoA reductase inhibitors (statins) • Antianginal drugs • Nitroglycerin; blockers; Ca2+ antagonists