Drugs Flashcards
Loop Diuretics
Inhibit NaCl reabsorption in the loop of Henle.
Strong and fast acting but short lasting.
eg: frusemide
What is the basic idea behind diuretics?
Decrease blood volume
> decrease preload and afterload
>decrease cardiac output
= less strain/O2 demand on heart.
Thiazide diuretics
Inhibit NaCl reabsorption in the distal tubule. This leads to decreased water absorption into the blood stream via osmosis.
Safe but weak.
eg: bendrofluazide
Potassium sparing diuretics
Weak, usually used in combination with others.
Can ^K
eg: Spirolactone
Diuretics - side effects
electrolyte imbalances (Us, Es, hypokalaemia)
Hypotension
^Uric acid
B-blockers work by?
inhibiting B1 receptors (sympathetic)
>reduce HR and CO
>reduce work performed by heart
>reduce O2 demands
Side effects/worries with beta blockers?
Can mask signs of hypoglycaemia Cold hands and feet (vasoconstriction in peripheries) Sleep - nightmares etc Tiredness Impotence
DO NOT GIVE TO ASTHMATICS!!!
How does dopamine work?
In the opposite way to beta blockers - it increases heart rate and blood pressure.
Basic m.o.a of nitrates?
Peripheral vessel dilators -> decrease preload.
M.o.a. of Ca channel blockers?
Dilates arteries (including coronary), leading to a reduced afterload and therefore workload and O2 demands of the heart.
Amlodipine is a…?
Ca channel blocker
ACE-inhibitors do what? How?
Reduce blood pressure.
Prevents vasoconstriction of both arteries and veins.
Blocks angiotensin II (a vasoconstrictor) which leads to reduction in aldosterone.
It can lead to renal failure.
What is amiodarone used for and how does it work?
Arrythmias - to reduce and stabilise HR
- in VT/VF arrest
Work by increasing repolarisation time to prolong the action potential.
Acts on: AVnode, purkinje fibres, cardiomyocytes.
What is quinidine used for and how does it work?
To reduce and stabilise HR in arrythmias.
Increases action potential threshold and refractory period.
Acts on cardiomyocytes, AVN, purkinje fibres.
Atropine: use and basic m.o.a?
Bradycardia
Antagonises (reduces) parasympathetic stimulation
> increases heart rate.
Use B-blockers in arrythmias caused by…?
MI
thyrotoxicosis
emotions
Uses and basic m.o.a of digoxin?
Heart failure - increases force of contraction Supraventricular tachycardia (SVT)
blocks Ca+ channels in the AVN and bundle of His
- increases refractory period - slows conduction
Adenosine - when would you use it and what does it cause?
SVT
transient heart block in the AV node.
Lignocaine - how does it work and what do you use it in?
0blocks Na+ channels
use in ventricular arrythmias (except VF/VT arrest)
What do aspirin and clopidogrel do?
Permanently block platelet activation sites.
Have to wait for new ones ~ long lasting!
