ACS/Stable Angina Flashcards
What are your approaches to treating stable angina?
- Increase or restore coronary blood flow through
- Surgery: CABG, PCI, Stent
Typically pharmacology is not helpful in increasing blood flow through the stenotic coronary artery into ischemic area
Talk about the bioavailability of nitrates
Significant first pass metabolism means that bioavailability through oral route is low
Isosorbide mononitrate is a poor substrate of nitrate reductase that is characterized by high bioavailability
What is the mechanism of action of nitrates?
Organic nitrates get metabolically active -> forms NO -> cGMP -> PKG
PKG -> opens potassium channels to hyperpolarize and reduce calcium entry
PKG -> myosin-LC-dephosphorylation and relax smooth muscle
What is the LEADING mechanism in stable angina?
Drop O2 demand
How does tolerance develop in nitrates?
Through depletion of thiol compounds that normally release NO, now NO is stuck and helps form superoxide radicals. This means no vasodilation, and SNS activation now.
Drug free for 8 hours to be okay
What are the adverse effects of nitrates?
- Headache (b/c meningeal vasodilation)
- Orthostatic hypotension
- Increase sympathetic discharge
- Increased renal Na+ and H2O reabsorption
Explain the interaction between nitrates and PDE5 inhibitors?
cGMP increased with nitrates
“Fils” prevent breakdown of cGMP
BP drops hella
What is the MOA of CCBs in stable angina?
- Decrease O2 demand
- Decrease PVR and afterload to drop BP - aftfects arterioles more than veins so less orthostatic hypotension
- Dihydropyridines work better
Drop contractility and HR
What is the major risk associated with nifedipine?
MI in pts with HTN, slow release and long acting are better tolerated
When does vasodilation trigger reflex sympathetic activation?
Short acting Dihydropyridine CCBs
What are the cardioactive CCBs and what does this mean?
Diltiazem and Verapamil - slows HR because drops HR
What is the MOA of Beta blockers?
Drop O2 demand
incidentally drops contractility and BP due to reduced afterload
What are some contraindications for beta blockers?
Asthma, PVD, Type 1 D, Bradyarrythmias, depressed function
What is the MOA of ranolazine?
Inhibit late Na+ current in cardiomyocytes targeting the LATE current by fast sodium channel responsible for phase 0 rapid depolarization
Pathologically NCX for Na/Ca remains open which brings in more calcium so we block this
What does ranolazine NOT affect?
HR and peripheral hemodynamics