cardiac medications (pharmacology) Flashcards
what is the equation for BP
BP= CO (HR x SV) x TPR
what are cardiovascular drugs used to treat
- hypertension
- angina, MI
- congestive heart failure
- arrhythmias
- cholesterol lowering
- blood disorders- anticoagulant (reduce blood clotting), anti platelet, thrombolytic
- anaemias, haemophilia
what are common groups of cardiac drugs
- diuretics
- sympathomimetics (mimic the sympathetic nervous system)
- a, B receptor drugs, nerve terminal drugs- calcium channel blockers (affect h ability of the receptor to make the way that the heart contracts)
- antigiotension antagonists- ACE inhibitors, receptor blockers
- anticoagulants
- statins
what are diuretics
- they target the kidney
- decrease the amount of fluid flowing though the veins and arteries by riding the body of sodium and water
- they are thiazides, loop diuretics and potassium sparing
mechanism of action of thiazides (type of diuretic)
- bendroflurazide
inhibits reabsorption of sodium and chloride ions in the distal convoluted tubule of the kidney and so initially reduce blood volume, cardiac output and blood pressure
mechanism of action of loop (type of diuretic)
- furosemide
acts primarily on the ascending loop of henle to inhibit the active transport of sodium and chloride from the nephron lumen to the interstitial fluid in the renal medulla
mechanism of action of K+ sparing (type of diuretic)
- amiloride, apirinolactone
competitively block aldosterone receptors in the distal convoluted tubule (DCT) reducing sodium reabsorption and potassium excretion
what to sympathomimetics (beta blockers) do
- increase cardiac contractility
- competitively block beta adrenergic receptors on the S.A and A.V nodes of the heart as well as on the ventricular muscle cells
- reduce heart rate and contracility and therefore cardiac output and blood pressure
- because the heart rate is reduced there is also more time for blood to move from the aorta to other areas of the circulation
- aortic blood pressure therefore reaches lower levels during diastole and so afterload is reduced
what are the disadvantages of beta-blockers
- fatigue/ depression
- vivid of bad dreams
- proaction of asthma
- cold peripheries
- possible conduction block or heart failure
- may increase serum triglycerides
sympathomimetics antiarrythmic drugs: Digoxin
- digoxin increases vagal (parasympathetic) activity
- inhibition of the sodium potassium APT pump with an indirect increase in intracellular calcium concentration in myocardial cells
- increased binding of actin and myosin
- increased force of myocardial contraction
vasodilators- calcium channel blockers
- change the way calcium moves in and out of the cells
- they block the calcium channels in vascular smooth muscle which causes less calcium to be available intracellularly and so the force of contraction is reduced- vasodilation and reduced TPR
Unwanted effects
- excessive vasodilation
- hypotension
- dizziness
- ankle oedema
- flushing
ACE inhibitors
- inhibit the activity of angiotensin converting enzyme which prevents the conversion of angiotensin 1 to angiotensin 2
- the reduction in circulating angiotensin 2 levels lowers BP by decrease vasoconstriction and decrease sodium and water retention
advantages of ACE inhibitors
- less aldosterone release from adrenal cortex and so less sodium and water retention
- reduced vasoconstriction
- less ADH release
- less thirst
- less cardiac and vascular smooth muscle hypertrophy
disadvantages of ACE inhibitors
- irritating cough
- angiodema- swelling of face, lips and airway
- may precipitate renal failure in patients with poor renal blood flow
- may cause potassium retention
what do anticoagulants do and what is their main side effect
- dissolve the clot by converting plasminogen into plasmin
- main side effect is bleeding
