Vasodilators 1 Flashcards
What are the three nitrate drugs called?
Glyceryl trinitrate, isosorbide mononitrate, isosorbide dinitrate.
How do nitrate drugs work?
Bind to receptor in vascular smooth muscle - causes formation of a NO group which stimulates guanylate cyclase to form cyclic GMP. Calcium entry is inhibited, causing vasodilation.
How do nitrates prevent cardiac work?
Because venous dilation reduces preload, which means the heart does not have to work as hard.
How can GTN be taken?
Sublingually or buccally or as a patch.
How long does it take for sublingual GTN to act?
Around 2 minutes.
In which clinical cases are nitrates used?
Angina, acute myocardial infarction, severe acute congestive failure.
How can nitrate tolerance occur?
After continuous therapy, due to SH group depletion. Can be reversed by SH donors.
What are the side effects of nitrates?
Flushing, headache, tachycardia, hypotension, methaemoglobinaemia (rare).
What name ending to most calcium channel antagonist drugs have?
-Dipine.
What type of channel do calcium channel blockers work on?
L type Ca ion channels.
How do calcium channel antagonists work?
They block the entry of calcium through calcium channels in vascular smooth muscle and myocardium, so less calcium is available for contractile apparatus causing vasodilation and a negative inotropic effect.
What type of calcium channels do diltiazem and verapamil favour?
Hyperpolarised calcium ion channels, found in cardiac muscle cells.
What are the side effects of calcium channel antagonists?
Headache, flushing, tachycardia, peripheral oedema, constipation, heart failure, heart block.
