Antianginal Good Views

8/13/2019 Antianginal Good Views

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Part 6 Antianginal Drugs

Organic nitrates

receptor blockers

Calcium channel blockers


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Coronary vessels:blood supply for the heart

1. OVERVIEW


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Coronary atherosclerosis:

cause of cardiac ischemia


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Distribution of coronary arteries in the heart


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Ischemia (angina pectoris):

imbalance between oxygen demand and supply


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Classification of angina pectoris:

Exertional angina ()Stable angina()Initial onset angina ()Accelerated angina ()

Spontaneous angina ()Angina decubitus ()Variant or vasospastic angina([])Acute coronary insufficiency ()Postinfarction angina ()

Mixed angina ()Unstable ang ina()

1. OVERVIEW


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Myocardial oxygen demandis chiefly

determined by:

Contractility

Heart rateWall tension

Preload (venous return )

Afterload (arteriolar resistance)

1. OVERVIEW

preloadafterload


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Myocardial oxygen demandisdiminishedby:

Reducing contractility Reducing heart rate

Reducing the preload

Reducing the afterload

1. OVERVIEW

Wall tension


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1. OVERVIEW

Myocardial oxygensupplyis chieflydetermined by:

AV oxygen difference

Regional myocardial

distribution

coronary blood flow: vascular r esistance, artery pressure


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Effects of antianginal drugs:

Reducing oxygen demands

Reducing heart rate and contractility

Dilating systemic arteries and veins ( wall tension bylowering heart loads)

Increasing oxygen supply

Dilating conduct coronary arteries ( coronary blood flow)Promoting regional distribution ( in ischemic regions)

Others:

Anti- platelet coagulation and thrombus formation

1. OVERVIEW


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2.1 Nitrates

Nitroglycerin )A. Pharmacological actions

Dilating vessels and reducing heart loads

wall tension ; reflex tachycardiaRedistr ibution of coronary circulation

dilating conduct artery:collateral circulation

reducing wall tension:

blood flow in ischemic subendocardial area

2. Antianginal drugs


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Influence of organic nitrates and dipyridamole

on the blood supply of ischemic area



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Mechanism of the effect of nitroglycerin and other nitrates



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Mechanism of the effect of nitroglycerin and other nitrates


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B. Clinical usesAngina pectoris: all kinds, especially stable type

Heart failurereducing heart loads due to vasodilation

C. Adverse reactions

Increase in heart rate and contractility

Symptoms due to vasodilation: headache, flash, postural

hypotension, collapse, ect.Others:methaemoglobinaemiaTolerance : avoiding steady-state plasma concentration;

supplement of agents containingSH (captopril)



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2.1 Other nitrates

Isosorbide dinitrate )

Isosorbide-5-mononirate (5-

)Compared with nitroglycer in:

Similar but weaker effect

Acting slowly but lasting longer

Larger individual variation and more adverse effects



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2.2 receptor blockers

A. Pharmacological action

Reducing oxygen demand:

heart rate and contractility I ncreasing oxygen supply:

diastolic period : perfusion time vascular tone in normal regions : blood flow in ischemic regions Others:

Improving myocardial metabolism

Inhibiting coagulation of platelets



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B. Clinical usesstableand unstablepectoris, especially associated with

hypertension or arrhythmias, even with myocardial infarction; but not

used forvariant angina pectoris

C. Notes

Dose individualization: starting from small dose

Withdraw gradually and slowly: symptomrebound

Combination with nitroglycerin



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2.3 Calcium channel blockers



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2.3 Calcium channel blockers

A. Pharmacological actions

Reducing myocardial oxygen remand: heart loads : nifedipine heart rate and contractility:verapamil and diltiazemI ncreasing myocardial blood supply

Protecting ischemic myocardial cel ls

I nhibiting coagulation of platelets



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B. Clinical uses

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 and diltiazem are similar to those of blockers


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2.4 Other drugsACEIs Treating hypertension and preventing ischemic heartdisease

Reducing heart loadsI nhibiting cardial remodeling

Nicorandil Opening ATP-sensitive K+channel (K

ATP)

Lower ing intracel lular Ca2+

Providing NO (l ike ni troglycer in)

I nducing ischemic preconditi oning



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Molsidomine I nhibiti ng adenosine uptake and cAMP degradation

I nhibiting pletelet aggregation

Promoting collateral circulation after long-term use

Dipyridamole I nhibiti ng adenosine uptake and cAMP degradation

I nhibiting pletelet aggregationPromoting collateral circulation after long-term use



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nitroglycerin blockers Ca2+antagonists combination*Heart rate Contractility /Wall tension / /Oxygen demand Blood pressure : increase, : markedly increase; : decrease, : markedlydecrease; : 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

3. Summary of antianginal drugs


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SammaryCardiovascular

pharmacology


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Overview o f Card iovascu lar Diseases

Common Cardiac Diseases

Abnormal contractilityHeart failures Abnormal rhythmsArrhythmias Abnormal blood supplyIschemic heart diseases Myocardial disorders

Common vascular diseases Abnormal systematic resistanceHypertension Dysfunction of coronary vesselsCoronary vascular diseases

Dysfunction of cerebral vesselsCerebral ischemia, hemorrhage Dysfunction of pulmonary vesselsPulmonary hypertension Dysfunction of peripheral vessels: Peripheral vascular disorder

Arteriosclerosis: basis of most CVS diseases


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Overview of Cardiovascu lar Drugs

Classification based on target organs/tissues

HeartHeart failures, arrhythmias, cardiac ischemia VesselsVasodilatation, vasoconstriction,

arteriosclerosis

Classification based on the mechanisms Ion channelsCa2+, Na+, K+ channels ReceptorsAdrenoceptors, AT1receptors, etc.

EnzymesACEI, Na+-K+-ATPase, HMG-CoAreductase

OthersDiuretics


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Cardiovascu lar 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

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