Anti-anginal drugs Jeff Flashcards
What affects supply of coronary blood flow?
Aortic diastolic pressure, duration of diastole (time at which ventricles get blood flow through coronary arteries), ejection fraction (if higher, less end-diastolic pressure), O2 delivery (anemia and CAD affecting perfusion)
What affects demand of heart?
Heart rate, Intraventricular wall pressure, Pre-load (increase pressure), afterload takes more energy, Contractility, Transluminal wall thickness
What is Prinzmetal’s Angina?
It is a variant angina. AKA nocturnal angina b/c recumbent position increases venous return which triggers alpha-adrenergic coronary vasospasm as it activates the stretching pressor response of coronary vaso beds
What is Dipyradamole and what is the mechanism?
Fast Acting Vasodilator (Persantine is trade name). It vasodilates to decrease peripheral resistance (more arterial than venodilation)
What are favorable effects of Dipyradamole?
Less afterload resulting in higher EF, less end diastolic volume and wall tension, decreased work demand, vasodilation in coronary vasculerature, increased coronary blood flow
Why isn’t dipyradamole used to treat angina?
Unfavorable effects occur. Drop in arterial pressure causes baroreceptor stimulation so higher heart rate increasing demand and risk of alpha vasospasm.
ALSO Coronary steal phenomenon (which is when TPR drops and blood goes there b/c little resistance and less flow to coronary arteries. Note: coronary arteries are already dilated after the drug is used, so hypoxic metabolites don’t allow it to reduce pressure enough to cause reperfusion when TPR is so low)
What is Persantine Stress Test?
Do it when person can’t do classic stress test. Inject Persantine, dire acting vasodilator, which causes heart to race due to baroreceptor reflex responding to drop in BP to put stress on heart.
How do organic nitrates and nitrites work?
Liberate NO to activate guanylate cyclase to make more cGMP to stimulate dephosphorylation dependent inactivation of myosin light chain to vasodilate veins more so than arteries at therapeutic dosage
Advantage of organic nitrates over direct acting vasodilators?
Less action on arteries at therapeutic dosage so TPR stays higher to prevent the baroreceptor reflex while still reducing stretching and preload of the heart from decreased venous pressure.
How does decreased preload help with angina?
Less stretching puts less pressure on coronary arteries so more blood flow to subendocardium where blood is lacking during angina. Decreases left ventricular pressure and less pulmonary vascular pressure too.
Which drug must you be careful about short shelf life?
Nitroglycerine will break down quickly, especially photosensitive so in amber glass bottle. Note: if tongue doesnt burn (from vasodilation), the drug isn’t working
Who gets “Monday Disease,” what are the symptoms, and why does it happen?
People who often work with nitroglycerin
Build tolerance during the course of the week and then lose tolerance over the weekend…re-exposure on Monday dilates cranial vessels–> headache
Adverse effects of nitrates?
High dose is orthostatic hypotension, meningeal vasodilation. Tolerance, dependence (Monday disease), high dosage can cause methemoglobinemia. IT IS CONTRAINDICATED in phosphodiesterase 5 inhibiters (viagra, cialis, levitra…) b/c that enzyme breaks down cGMP (or NO, which one, Joe?)
Indications of nitrates?
Angina, variant angina, CHF
How are nitrates eliminated?
Liver for all of them, all protein bound
Which nitrate has a longer half life (5 hours)?
Isosorbide-5-mononitrate (notice there is a 5 in the name, like the half life of it)
