Classification of angina



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Angina pectoris

  • Sudden severe pressing chest pain starting substernal & radiate to left arm,lower jaw.

  • Due to imbalance between myocardium oxygen requirement & oxygen supply

  • Risk factor: Age, Sex, Smoking, Obesity, Diabetes




  • Classification of angina:

  1. Exertional angina (Stable, Atherosclerotic, CLASSIC): Due to obstruction of coronaries by atheroma

  2. Variant (Vasospastic, Prinzemtal): Due to spasm of coronaries.

  3. Unstable (occurs at rest) : due to spasm & partial obstruction of coronaries

  4. Silent angina (acute – occurance of myocardial infarction is common – rate of death is high) .




    • Treatment :

Nitrates & nitrites >>>> nitrites are not used any more b/c it causes "methemoglobenemia" .


  • PREPARATIONS:

1. Short acting: start with few min & total duration of action is 15-30 min

  1. Nitroglycerine (glyceryl trinitrate ) MCQ***** [used as sublingual tablets]

  2. Isosorbide dinitrate (sublingual spray )

  3. amyl nitrate (inhalation of valatine vapor) >>> not commonly used .

2. Long acting :( rapid onset)prophylaxis >>> are not used for treatment of acute attaks .

  • Nitroglycerine, Isosorbide dinitrate, Isosorbide mononitrate, Erythrityl Trinitrate . N.B : isosorbide mononitrate is

  • delayed onset of action & continue for hours. the active metabolite of isosorbide

  • They are given: orally, ointment, buccal, transdermal, patch, parentral. Dinitrate.




  • Absorption: well absorbed according to the route:

  • GIT long acting I.V nitroglycerine or the infusion is the

  • Sublingual or inhalation short acting treatment of myocardial infarction b/c

  • Transdermal long acting it's long lasting and has rapid onset of

Action .

  • Metabolism: through first pass hepatic metabolism .

  • Short acting having a low oral bioavailability 10-20% , so not given orally to avoid 1st pass metabolism.

  • Nitroglycerine metabolism (2 dinitro & 2 mononitro form)

  • The dinitro form are active metabolites & have significant vasodilator effect.

  • Isosorbide dinitrate metabolite (5-mononitrate) is an active metabolite used clinically.

  • Excretion : mainly through kidney

.

  • Mechanism of action:

Nitroglycerine Glutathione S-transferrase NO (nitric oxide)

  • NO activates guanylyl cyclase & ↑ cGMP

  • cGMP dephospholyrates myosin light chain (Myosin-LC-PO4) active to( myosin LC) inactive→

causing muscle relaxation.

  • Pharmacological actions :

Nitrates relax all types of smooth muscles, vascular or non vascular Nitrates are considered as

  • Relax both arteries & veins but more effective on veins venodilatores .

  • They have no direct effect on cardiac or skeletal muscles

  • NO released stimulate guanylyl cyclase in platelet causing ↑ cGMP that ↓ platelet aggregation.

  • Clinical uses:


Effect of these drugs on all types of angina (underlying mechanism) :

  1. Angina of effort :

  1. Decrease venous return .(Dec. load on the heart) vasodilatation of middle meningeal

  2. Decrease BP. Artery causes increase in the intra-

  • Both (A) & (B) decrease myocardial oxygen requirement (myocardial work) cranial pressure .

  1. Redistribution of coronary blood flow.

  2. Antiplatelets effect.(dec. thrombus formation) vasodilatation in general causes

hypotension accordingly, the

2. Variant angina: body compensate by inducing

Relax smooth muscle of epicardial coronary artery and relief coronary spasm. Reflex tachycardia, salt-water



Retention & throbbing headache.

  1. Unstable angina :

  • Relief coronary spasms.

  • Decrease platelets aggregation.




  • Adverse effects:

  1. Orthostatic hypotension and syncope.

  2. Throbbing headache.

  3. Tachycardia.

  4. Facial flushing.

  5. Tolerance.

  6. Salt and water retention.

  7. Carcinogenicity  b/c of the compound "nitrosamine" present in nitroglycerine but the incidence

of carcinogenicity is not proved yet in humans .

  1. Methemoglobinemia only with nitrites .




  • Contraindications :

  • Nitrates are contraindicated in increased intracranial pressure .

  • Notice: nitrates can be used safely in the increase of intraocular pressure (glaucoma) .




  • Calcium channel blockers (arteriodilators only) :

  1. They block calcium entry in myocardium causing :

    1. Decrease myocardial contractility and myocardial oxygen requirement.

    2. Decrease heart rate causing decrease in myocardium oxygen requirement.

  2. Block calcium entry in vascular smooth muscles (arteries and arterioles) causing :

    1. Decrease in peripheral resistance (after load)  decrease in oxygen requirement.

    2. Relief of coronary spasm.



  • Clinical uses :

  • In all types of angina but very effective in variant angina.

  • Used mainly in prophylactic therapy.




  • Β-adrenoceptor blocking drugs (used as prophylactics) :

  • They are not used as vasodilators. >>>> therefore, they are noe indicated in treating vaso-spastic angina .

  • They are used in treatment of angina.

  • They reduce both HR and myocardial contractilitydecrease myocardial O2 requirement at rest and

in exercise so improve exercise tolerance .


  • Clinical uses:

  • They are effective in prophylactic treatment of classic and unstable angina.

  • They are not used in variant angina.

  • They are effective in treatment of silent (ambulatory angina –no pain).

  • Dec. mortality of patients with recent myocardial infarction.




  • Potassium channel openers(Nicorandil)

  • Activation of potassium channels

  • Nitric oxide release.

  • Arterio and veondilators.(equally)

  • Used in prophylactic therapy.

  • May cause:headache,flushing,dizziness.




  • Anticoagulants and antiplatelets:

Aspirin and heparine decrease the risk in the unstable angina and acute coronary syndrome.


  • Fatty acid oxidase inhibitors:

  • Oxidation of FA as a source of energy needs more O2 than the oxidation of carbohydrate.

  • Drugs that shift myocardial metabolism toward using glucose (FA oxidase inhibitors) have the

potential of reducing the O2 demand without changing the hemodynamics eg. Trimetazidine.


  • Drug treatment of angina pectoris :

  1. Acute attack: short acting nitrates or nitrites.

  2. Prophylactic therapy:

  1. Long acting nitrates.

  2. Ca-channel blocker.

  3. β-adrenoceptor blockers.

  4. K-channel openers.

drug in prophylactic therapy.


  • Combination therapy:

  1. Nitrates & β-adrenoceptor blocker.

  2. Ca-channel blocker ( dihydropyridine) acting mainly on blood vessles & β-adrenoceptor blocker .

(Using other classes of Ca-channel blocker (acting mainly on heart) , with β-adrenoceptor blocker

may cause cardiac arrest ) .



  1. Ca-channel blocker & nitrates.

  2. Ca-channel blocker, β-adrenoceptor blocker , nitrates , antiplatelets or anticoagulant .




  • Surgical therapy:

  • Ballon .

  • Coronary bypass.



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