Stable and Vasospastic Angina Drugs Flashcards
What is stable angina
occlusion of coronary arteries resulting from the formation of atherosclerotic plaque
- Most common form of angina
- Symptoms occur during exertion or stress
What’s vasospastic (variant angina?
episodes of vasoconstriction of coronary arteries
- Likely genetic in origin
- Symptoms occur at rest
- Much less common than classic angina
What are approaches to angina tx?
- DECREASE CARDIAC WORK –> reduce O2 demand
- INCREASE BLOOD FLOW THROUGH CORONARY ARTERIES –> increases O2 supply
How can coronary blood flow be increased/restored to treat angina?
- Coronary artery bypass grafting
- Percutaneous coronary intervention (PCI)
- Stent – expandable tube used as scaffolding to keep vessel open
– Pharmacotherapy is not effective in increasing blood flow through the stenotic coronary artery into the ischemic area
What determines myocardial O2 demand?
– Heart rate
– Contractility
– Preload
– Afterload
What Drug classes are used to treat angina? (4)
- nitrates
- Calcium channel blockers
- Beta blockers
- Ranolazine
Nitrolgycerine is a …?
Nitrates (nitrovasodilators)
isosorbide dinitrate is a..?
Nitrates (nitrovasodilators)
Isosorbide mononitrate is a…?
Nitrates (nitrovasodilators)
- isosorbide mononitrate is a poor substrate of nitrate
reductase–> has higher Availability
Describe nitrate pharmacokinetics`
Significant first-pass metabolism – high nitrate reductase activity in the liver
• Bioavailability with oral route is low
• Other routes that avoid first-pass metabolism are used
• Partially denitrated metabolites may still have activityand longer half-lives
•
What enzyme do nitrates target?
produce NO –> targets guanylyl cyclase to cause
-hyper polarization and reduce calcium entry
- Smooth muscle relaxation
How do nitrates reduce O2 demand?
Nitrate-> NO-> Venous dilation-> reduced preload-> decreasedO2 demand
What depletes tissues of NO?
increased generation of superoxide anions
What are short acting Nitrates? Use?
- sublingual Isosorbide dinitrate
- sublingual Nitroglycerin
-Short-acting formulations are used to relieve the angina attack
What are long acting nitrates? Use?
- Nitroglycerin - oral/ointment/patch
- Isosorbide dinitrate - oral
- Isosorbide mononitrate - oral
What are the adverse effects of nitrates
- Headache (due to meningeal vasodilation) – Nitrates are contraindicated if intracranial pressure is elevated
- Orthostatic hypotension
- Increased sympathetic discharge (Tachycardia, Increased cardiac contractility)
- Increased renal Na+ and H2O reabsorption
What drugs do nitrates interact with?
ERECTILE DYSFUNCTION DRUGS – Sildenafil - Vardenafil – Tadalafil • Inhibit cGMP-> increase cGMP--> DRAMATIC BP DROP - can cause acute MI
What are the 2 types so calcium channel blockers?
- Non-cardio active/dihydropyridines (don’t reduce HR)
2. Cardioactive (Reduce HR)
What are the dihydropyridines (non-cardioactive) CCBs?
• Nifedipine (Adalat) (short-acting, t1/2 4 h)
-Amlodipine (Norvasc) (long-acting, t1/2 30-50 h)
• Nicardipine (Cardene) (short-acting, t1/2 2-4 h)
**NAN cardioactive CCB
What are the cardioactive CCBs?
- Diltiazem (Cardizem)
* Verapamil (Isoptin)
What are the targets of Dihyropyridines?
Non-cardioactive CCBs target vascular smooth muscle
What are the targets of cardio active CCBs?
- Vascular smooth muscle
- Cardiac muscle
- Cardiac pacemakers cells
How do CCBs treat stable angina?
decreased myocardial O2 demand
How do CCBs decrease myocardial O2 demand in stable Angina?
- Dilation of peripheral arterioles (Decreased PVR and afterload, decreased blood pressure)
– Arterioles affected more than veins (less orthostatic hypotension)
– Both cardioactive CCbs and dihydropyridines are effective but dihydropyridines are more effective vasodilators - Decreased cardiac contractility
– Observed with cardioactive CCBs only - Reduced heart rate
– Observed with cardioactive CCBs only
What are the adverse effects of CCBs?
• Major
– Cardiac depression, cardiac arrest, and acute heart failure (cardioactive CCBs)
– Bradyarrhythmias, atrioventricular block (cardioactive CCBs) – Severe hypotension – Short acting dihydropyridine CCBs – vasodilation triggers reflex sympathetic activation
– Nifedipine (immediate release) increases the risk of MI in patients with hypertension – slow-release and long-acting dihydropyridines are better tolerated
• Minor
– Flushing, headache, anorexia, dizziness
– Peripheral edema
– Constipation (verapamil) 23
What beta blockers are used to treat stable angina?
– Propranolol (Inderal)
– Nadolol (Corgard)
– Metoprolol (Toprol)
– Atenolol (Tenormin)