Drugs for Ischemic Heart Disease - Konorev Flashcards
2 ways to treat angina pectoris
- Decreased cardiac work (i.e. oxygen demand)
- Increase blood flow through coronary arteries
When are vasodilators most useful in treating angina?
Prinzmetal (vasospastic) angina
Coronary steal phenomenon
Why NOT to use vasodilators in atherosclerotic angina…
- Dilate un-blocked arterioles –> LESS collateral flow around block to blocked arterioles
4 determinants of myocardial oxygen demand (to be altered in angina)
- HR
- Contractility
- Preload
- Afterload
3 drug classes used in chronic ischemic heart disease
- Nitrates (vasodilate)
- CCBs (vasodilate, slow HR)
- Beta-blockers (slow HR)
3 nitrovasodilator drugs
- Nitroglycerin
- Isosorbide dinitrate
- Isosorbide mononitrate
Function of endothelium on vascular relaxation
- Nitric oxide release w/ ACh or bradykinin stimulation
Describe N.O. release following stimulation of endothelium
Receptor –> calcium release –> calmodulin –> NOS active –> arginine converted to NO –> released onto SM
Molecular pathway of N.O. on muscle cell
Activates guanylyl cyclase –> cGMP –> K+ channel opens and myosin LC dephosphorylation –> hyperpolarization and SM relaxation
2 functions of nitrates at low concentration
Dilate VEINS and LARGE arteries, inhibit platelet aggregation
Benefit of nitrates vs. other vasodilators in atherosclerotic angina
No coronary steal phenomenon since arterioles not affected
MOA of nitrates in treating atherosclerotic angina
- Dilate veins –> reduced preload
- Dilate arteries –> reduced pressure
EFFECT = DECREASED O2 DEMAND OF HEART
MOA of nitrates in treating vasospastic angina
Coronary artery relaxation
Most short acting formulation of nitrates
Used for?
Sublingual or spray nitroglycerin (10-30 min)
Relieving current attack
Most long acting formulation of nitrates
Used for?
Oral nitroglycerin or isosorbide (4-10 hours)
Prevent future attacks