General vasodilator, greater effect on venous circulation
What is the MOA of Nigroglycerin?
Increases venous capacitance (decreases preload) Small deception in systemic arterial BP (decreases afterload) Coronary dilator
Nitrate, 25% orally bioavailable, longer DOA (4-6 hours)
Nitrate, No 1st pass metabolism, 1/2 life 5 hours
Can a tolerance be built up to Nitrates?
Yes - if uses for more than a few hours. But it reverses rapidly (24 hours). Limits effectiveness of slow release forms.
Antagonize voltage-gated Ca2+ channels
Ca2+ Channel Blockers
What are the two classes of Ca2+ channel blockers?
Dihydropyridines: Nefedipine, Amlodipine Non-Dihydropyridines: Verapamil, Diltiazem
What is the MOA of Dihydropyridines?
Potent vasodilators Decrease O2 demand (decrease after load) Increase O2 by coronary vasodilation Relief for vasospasm --> Prinzmetal angina
What is the MOA of non-Dihydropyridines?
Vasodilators Relieve ischemia by decreasing O2 demand by decreasing the force of contraction and HR
What are some side effects of Ca2+ channel blockers?
Headache Flushing Decrease contractility (V/D) Bradycardia (V/D) Edema (N/D) Constipation(V)
Anti-anginal by decreasing O2 demand through decreasing the force and HR d/t blockade of endogenous catecholamines.
B-Adrenergic Receptor Blockers
What is the MOA of B-blockers?
Slowing the HR increases BF to ischemic areas by increasing the time in diastole
What are some side effects of B-blockers?
Avoid in patents with obstructive airway disease Not to be used in patients with acutely decompensated heart failure, bradycardia and heart block Use caution in diabetes with insulin Fatigue Sexual dysfunction
Decreases the frequency of anginal episodes and increase exercise capacity Possibly works by inhibiting I(Na) in cardiac myocytes
When do you use ACE inhibitors?
After MI to decrease mortality, especially if LV ejection fraction is low