Drugs used in ischemic heart disease Flashcards
Nitrates:
General vasodilator, but much greater effect on venous blood vessels.
Work by increasing venous capacitance (decreasing preload); result in reduced diastolic wall tension.
Small reduction in afterload.
Large first pass effect: nitroglycerin is given sublingually for acute therapy. Can also be used chronically.
SE: reflex tachycardia.
B blockers:
Decrease the force of ventricular contraction, heart rate, afterload due to blockade of B1 receptors. Can improve blood flow by prolonging diastole.
Can precipitate the incidence of vasospasm, so don’t give in angina cases. NO CHF PATIENTS. Don’t give non-selective (propranolol, timolol) to asthmatic patients.
Calcium channel blockers:
Antagonize voltage-gated L-type calcium channels. Dilation of smooth muscle, decrease AV nodal conduction and muscle contractility.
Name the dihydropyridines (2) and the non-dihydropyridines (2):
Dihydropyridines: nifedipine, amlodipine.
Non-dihydropyridines: verapamil, dilitazem.
Dihydropyridines vs non-dihydropyridines MOA:
Dihydropyridines: relieve ischemia by decreasing oxygen demand and increasing oxygen supply via potent vasodilation. Great at relieving vasospasm.
Non-dihydropyridines: relieve ischemia by decreasing oxygen demand by reducing the force of contraction and heart rate. Not so great at vasodilating.
Explain the benefits of giving B blockers and nitrates together:
B blockers prevent the potential reflex tachycardia associated with nitrates.
Nitrates prevent the potential increase in wall tension produced by B blockers.
Ranolazine:
Antianginal agent. Believed to inhibit the late sodium current in cardiac myocytes.
What are the stress test agents?
Dobutamine: causes increase in heart rate and contractility to simulate exercise.
Adenosine: used to cause arterial dilation - normal coronaries will dilate in response to adenosine (or exercise), but diseased vessels will not be able to dilate as much. This difference can be seen on imaging.
