Antianginals Flashcards
Myocardial ischemia results from an imbalance between…
O2 supply vs O2 demand
Classic or atherosclerotic angina is caused by…
Atheromatous obstruction of large coronary vessels esp with exercise
May require coronary bypass or angioplasty
Variant, angiospastic, or Prinzmetal’s angina is caused by…
Spasm or constriction in atherosclerotic coronary vessels
Reversible by nitrates or CCBs (NOT BBs)
Any increase in heart rate or contractility will…
Increase the need for O2
O2 demand depends on cardiac workload, determined by HR, contractility, and ventricular wall tension
Coronary flow may be decreased by…
Shortening diastole when HR increases
Increased ventricular end-diastolic pressure
Reduced diastolic arterial pressure
MOA for Nitrates/Nitrites in angina
Vasodilation via NO —> cGMP
Causes UNEVEN vasodilation - large veins are markedly dilated —> increased capacitance and reduced preload; arterioles and precapillary sphincters less dilated but will still decrease afterload
DOC for any acute anginal attack
Nitrates/nitrites
Provide relief by reducing myocardial O2 requirement
Why is nitroglycerin administered sublingually?
High first pass metabolism
Rapid absorption
Immediate relief (within 1-3 min, lasting 10-30 min)
What is the main adverse effect of nitroglycerin?
Throbbing headaches (can also get orthostatic hypotension and tachycardia)
Frequent repeated exposure —> tolerance or marked reduction in effect
Which drug is connected to “Monday Disease”?
Nitroglycerin
Explosive manufacturers —> chronic exposure to nitrate —> headaches/dizziness on Monday but symptoms gone by Friday, reappear after weekend break
Which CCB is indicated only in HTN (not for angina)
Nifedipine
May provoke angina, esp if there is any underlying narrowing of the arteries
In general CCBs are good for _________ of angina
Chronic treatment, not immediate relief
Because you need VENOdilation
How do beta blockers provide anginal relief?
Reduced sympathetic activity —> direct decrease in HR and vasoconstriction —> hypotension/bradycardia —> decreased cardiac workload —> decreased myocardial O2 demand
The bradycardia also increases myocardial perfusion time
They are NOT vasodilators!
Which anti anginal drug is contraindicated in Prinzmetal’s angina?
Beta blockers
Because they don’t cause vasodilation
Side effect of BBs used in angina
Bronchoconstriction
Increased plasma TGs
Decreased insulin and hypoglycemic response
CNS side effects
What does Ranolazine (Ranexa) do for angina?
Partial fatty-acid oxidation inhibitor —> reduces O2 consumption in ischemic tissue
Also inhibits late inward Na current —> decreased contractility
Basically, it IMPROVES CORONARY CIRCULATION
Used when other antianginal drugs don’t work
Effective therapy for angina pectoris will…
Increase exercise tolerance
Decrease frequency and duration of myocardial ischemia
For variant or angiospastic angina:
Nitrates and CCBs preferred b/c BBs will not dilate vessels
Patients with angina and PEPTIC ULCERS should use what drugs?
BBs or organic nitrite/nitrate
NOT CCBs b/c relaxing the smooth muscles will reduce gastric emptying and increase acid effects
Drug originally developed as an antianginal agent but found to be more effective for ED
Sildenafil (Viagra)
Selective inhibitor of cGMP-specific phosphodiesterase type 5
Why does viagra cause visual impairment?
B/c PDE is also in the retina —> mild and transient blue color tinge to vision, photophobia, or blurred vision
Pilots can’t take 8 hours before flying
Contraindications for Sildenafil (Viagra)
Pregnant or lactating women 😂
Patients concurrently using organic nitrates/nitrites in any form (b/c vasodilation —> LOC)
Concurrent dosing with alpha blockers may lead to symptomatic hypotension
Inhibitors of CYP3A4 —> toxicity
Other PDE5s besides Sildenafil
More selective for PDE5 than PDE6, so less visual disturbances
Vardenafil and Avanafil (work “V”ery soon)
Tadalafil (works “T”omorrow) - good for a whole weekend of fun
