19. Drugs To Treat CVS Flashcards
How do beta blockers work in the CVS?
Competitive reversible antagonists block action of sympathetic NS. Decrease BP, HR, SV, CO
What are the adverse effects of beta blockers?
Exacerbate asthma, intolerance to exercise, hypoglycaemia, vivid dreams
How do alpha blockers work in the CVS?
Competitive reversible antagonists block sympathetic tone in arterioles. Decrease peripheral resistance
What are the adverse effects of alpha blockers?
Postural hypertension, reflex tachycardia
How do ACE inhibitors work?
Reduce formation of AT-II (vasoconstrictor) and reduce blood volume (no stimulated release of aldosterone)
What are the adverse effects of ACE inhibitors?
Sudden fall in BP on first dose, persistent cough
How do AT-II receptor blockers work?
Block actions of AT-II to reduce BP
How do diuretics work?
Lower BP by decreasing blood volume. Reduce renal reabsorption of Na+ and water
How do calcium channel blockers work?
Block L-type voltage-operated calcium channels to stop Ca2+ entry causing depolarisation + contraction. Reduce TPR and CO
Which calcium blocker drugs are smooth muscle and cardiac muscle most sensitive to?
Smooth muscle: nifedipine > diltiazem > verapamil
Cardiac Muscle: opposite
What are adverse effects of calcium blockers?
Headache, constipation, cardiac dysthymias, gum hyperplasia (overgrowth)
Why does angina pectoris occur?
Due to myocardial ischaemia resulting in a build up of metabolites in the chest which activates sensory nerves. Causes pain
When increased myocardial O2 demands are not met
What are the three types of angina?
Stable - attacks during exercise, due to occlusion in coronary artery (need cholesterol-lowering drugs)
Unstable - unpredictable attacks, occlusion due to platelet adhesion to ruptured plaque (need anti-platelet drugs)
Variant - vasospasm of coronary artery
How is angina treated?
By decreasing the myocardial O2 demand with vasodilator drugs
How do angina drugs work?
Block SA node depolarisation so HR decreases but not force of contraction - decreases myocardial O2 demand
What is the Bainbridge reflex?
What does it cause?
A sympathetic reflex initiated by increased blood in the atria.
Causes stimulation of SA node and baroreceptors in atria -> increased sympathetic NS stimulation
How are nitrovasodilators used?
To treat angina. Rapid action but short lived. Taken immediately before exercise or for relief during angina attack
What type of dilation do nitrovasodilators cause?
Venous dilatation is greater than arterial.
What are the causes of heart failure?
Hemodynamic overload due to excess pressure or volume
Neurohumoral overload
Tissue damage ie MI
Genetic response
What are the symptoms of L ventricular failure?
What are the symptoms of R ventricular failure?
Fatigue, pulmonary oedema
Venous distension, oedema
How is heart failure treated?
Try to reduce preload/afterload or make heart work harder
Use diuretics or ACE inhibitors
Also positive inotropes
Which positive inotropes are used for heart failure?
When would they be used?
Dopamine and Dobutamine - make heart work harder
Used when heart failure patients have not responded to standard treatment
What do calcium sensitisers do?
Increase contractility of the heart by increasing amount of calcium bound to troponin-C
How do digitalis compounds work?
Increase contractility of the heart to treat heart failure by increasing intracellular calcium. Makes more calcium available to bind to troponin-C
What is considered a “good” lipoprotein?
HDL, small in size. Large VLDL are bad
How do statin drugs work?
Inhibit cholesterol biosynthesis to decrease cholesterol levels.
