treatment of SCAD Flashcards
What is the protype of nitrates/nitrites?
nitroglycerin (GTN)
What do nitrates directly act on and what do they do to them?
blood vessels
vasodilation (widen blood vessels)
What is a prodrug?
the drug needs to be converted in vivo to the biologically active metabolite
What is the active metabolite of nitrates?
NO nitric oxide
What does NO activate?
guanylate cyclase
Wat does guanylate cyclase do?
convetrs GTP to cGMP
which activates PKG
causes vasorelaxation
What group in NO interact?
thiol groups
What is the main anti-anginal effect of nitrates?
- venodilation
- peripheral arterial/arteriolar dilation
- coronary vasodilation
Clinical uses of nitrates
- relief of angina attacks
- treats chronic angina
Adverse effects of nitrates
- headaches
- postural hypotension and syncope
- reflex tachycardia and increased myocardial contractility
- tolerance
How do you develop tolerance to nitrates?
- depletion of thiol groups
- physical adaptation
Recommendations for nitrate therapy
- begin with small dose
- establish threshold that achieves effect
- use lease amount needed
- avoid sustained action formulations
- plan to have a nitrate free interval of 8-10hrs
2 structural analogues of beta adrenoceptor antagonists
- analogues
- isoprenaline
Protypes of beta adrenoceptor
propranolol
atenolol
What is the pharmacological action of beta blockers?
antagonise the effects of the sympathetic nervous activation
2 classes of beta blockers
- non selective
- beta 1 receptor selective
Features of hepatic metabolism (beta blockers)
- lipid soluble
- completely absorbed from gut
- metabolised in liver
- variable bioavailability
- short plasma 1/2 life
Features of kidney metabolism (beta blockers)
- water soluble
- incompletely absorbed from gut
- eliminated unchanged
- less variable bioavailability
longer 1/2 life
Adverse effects of beta blockers
- increase LV size
- rebound phenomenon
- bronchoconstriction
- peripheral vasoconstriction
- myocardial depression
- mask signs of hypoglycaemia
- sexual disfunction
- CNS disturbances
How do calcium channel blockers work?
inhibit Ca entry into cells via voltage gates calcium channels
What cells do Ca channel blockers stop Ca entry into?
cardiac muscle cells
nodal cells
conducting cells
What effects do Ca blockers have on the heart?
decrease cardiac contractility
reduce HR
What vascular effects do Ca blockers have?
blocks Ca into arterioles which causes arteriolar dilation
What does peripheral vasodilation by Ca blockers do?
reduce SVR which reduces arterial BP
