Antianginal Drugs Flashcards
How is reduction of oxygen demand achieved?
Lowering HR, contractility, and/or cardiac wall tension
What are the main treatment goals of each type of angina?
Stable - reduce oxygen demand
Prinzmetal (variant) - reduce vasospasm
Unstable - increase blood flow or supply
How are increases in supply achieved?
Increases in blood flow
Sometimes redistribution of cardiac blood flow
What are the beneficial effects of vasodilators?
Reduced preload
Reduced wall tension via peripheral venous vasodilation
Coronary artery vasodilation
Inhibit coronary vasospasm
What are the hemodynamics effects of beta blockers?
Reduce myocardial oxygen demand
Increase oxygen supply by prolonging diastole
What are the adverse effects/toxicity of beta blockers?
Nightmares, etc
Not used in variant angina because of blockage of beta2 than can help vasospasm
Not used in asthma
Not used in acute heart failure due to decrease in CO
What can beta blocker be combined with?
Nitrates
Some of negative effect of each drug are reduced - reflex tachycardia from nitrates are reduced by beta blockade)
What is the molecular mechanism of calcium antagonists?
Bind to L type calcium channels in smooth muscle and decrease calcium entry
Verapamil and diltiazem, but not nifedipine, slow recovery of calcium channels that cause direct negative chronotropic and inotropic effects on heart
What are the hemodynamic effects of nifedipine?
Vasodilation of arterial system and reduce resistance
Reduces myocardial oxygen demand by dilating peripheral arteries (reduces LV after load)
Increases myocardial oxygen supply by inhibiting coronary vasoconstriction/vasospasm and dilating coronary arteries
What are the hemodynamic effects of verapamil and diltiazem?
Reduce oxygen demand by arterial vasodilation and decrease in after load
Modest decrease in contractility
Diltiazem causes modest decrease in HR
increase oxygen supply by dilating coronary arteries and inhibiting their vasoconstriction
What is the molecular mechanism of organic nitrates?
Metabolized to release vasodilator NO
Stimulates guanylyl cyclase to increase cGMP that activates dependent kinase that enhances uptake of calcium into SR
Lowers intracellular calcium and causes smooth muscle relaxation
What are the hemodynamic effect of organic nitrates?
Reduce demand by dilating peripheral veins and diminishing preload
Lesser extent dilate peripheral arterioles and decrease afterload
Only cause mild reflex symp stimulation because primarily dilate venous system
Veins dilate at low doses but arterioles not til higher doses
Increase myocardial oxygen supply by dilating larger epicardial vessels
What are nitrates the mainstay for?
Stable angina
What is nitroglycerin and how is it absorbed?
Nitrate - prototype for treatment of acute angina
Rapid sublingual and oral absorption - sublingual faster
Short duration of action
Bioavailability of oral is low due to first pass hepatic metabolism
Absorption of topical preps is slower
IV can be titrated rapidly in emergencies due to short half life
What is the fate/excretion of nitroglycerin?
Elim by kidney
