ORGANIC NITRATES AND PDE INHIBITORS Flashcards
What is the clinical use of organic nitrates?
Relief of angina pain - used prophylactically
Nitrovasodilators are prodrugs. What are they converted into?
Nitric oxide
What is the mechanism of action of organic nitrates?
Nitrovasodilator is a prodrug that is converted to NO
NO activates soluble guanylyl cyclase which converts GTP to cGMP
cGMP then activates PKG which leads to phosphorylation of target protein
This leads to reduction in conc of calcium and vasodilation
Angina is a crushing pain under the sternum that radiates to towards left shoulder and arm. True or false?
True
What are the three kinds of angina?
Stable
Unstable
Variant
Stable angina occurs on exertion whereas unstable occurs at rest. True or false?
True
Nitrovasodilators relieve an angina attack by decreasing oxygen demand by reducing cardiac output. True or false?
True
The more stretched the cardiac muscle is at the end of diastole, the harder the heart has to work. True or false?
True - because the higher the SV and so higher CO. So by reducing the stretch, EDV is reduced and hence SV is reduced
Nitrovasodilators cause vasodilation in veins. True or false?
True - this reduces central venous pressure, venous return and hence preload
Why is GTN ineffective if given orally?
Inactivated by the liver
Isosorbide mono-nitrate is effective orally. True or false?
True
What is riociguat used for?
CTEPH - chronic thromboembolic pulmonary hypertension - causes increases in BP
How does riociguat work?
Activates secondary guanylyl cyclase - by either direct activation or enhancement of NO effects
cGMP and cAMP are broken down by what?
cyclic nucleotide phosphodiesterases?
How do phosphodiesterase inhibitors work in leading to vasodilation?
PDE is inhibited and so doesn’t break down cGMP and cAMP which allows the pathway to vasodilation to take place