Drugs Affecting Cardiovascular System (Blood Pressure) Flashcards
What is the definition of hypertension?
Blood pressure greater than 140/90
What does hypertension predispose you to?
stroke, TIA, myocardial infarction, ischaemic heart disease, aortic aneurism, retinal haemorrhage, renal failure
What are the risk factors for high blood pressure?
smoking, diet, weight, stress
How can BP be reduced without any drug intervention?
By reducing risk factors - smoking, alcohol, fats, salt, BMI and increasing exercise and relaxation
How does the sympathetic nervous system influence blood pressure?
By targeting alpha 1 adrenoceptors on arteries to cause vasoconstriction and beta 1 adrenoceptros on the heart to cause increase in heart rate and contractility and beta 1 adrenoceptors on the kidney to increase angiotensin II
What is the effect of the kidney on blood pressure?
Stimulation by the sympathetic nervous system causes increase in angiotensin II, angiotensin causes vasoconstriction, increase in aldosterone (water retention), cardiac cell growth and also feedbacks on the sympathetic nervous system
How does the renin angiotensin system work?
Renin converts angiotensinogen to angiotensin I and angiotensin converting enzyme converts angiotensin I to angiotensin II
What are the five classes of antihypertensive drugs?
Angiotensin system inhibitors, beta-adrenoceptor antagonists, calcium channel blockers, diuretics, other
What are the names for ACE inhibitors?
‘prils’ - captopril, enalapril, perindopril, ramipril
What is the action of ACE inhibitors?
Blocks conversion of angiotensin I to angiotensin II and also prevents bradykinin breakdown
What is the result of ACE inhibitors?
Reduced vascular tone, reduced aldosterone production, reduced cardiac hypertrophy
What are the adverse effects of ACE inhibitors?
first dose hypotension, dry cough, loss of taste, hyperkalaemia, acute renal failure, itching, foetal malformations
What are the contraindication in ACE inhibitors?
pregnancy, bilateral renal stenosis, angioneurotic oedema
What are the names for angiotensin receptor antagonists?
‘sartans’ - losartan, candesartan
What is the action of angiotensin receptor antagonists?
Blocks angiotensin receptors AT1
What is the result of angiotensin receptor antagonists?
Reduce vasoconstriction, reduce aldosterone, reduce cardiac hypertrophy, reduce sympathetic activity
What are the adverse effects of angiotensin receptor antagonists?
hyperkalaemia, headaches, diziness
What are the contraindications for angiotensin receptor antagonists?
Same as ACE inhibitors - pregnancy, bilateral renal stenosis, angioneurotic oedema
What are the names for beta adrenoceptor antagonists?
‘olols’ - propranolol, timolol (non selective) atenolol, metropolol (selective for beta 1), pindolol (partial agonist for beta 1 and beta 2)
What is the action of beta adrenoceptor antagonists?
Blocks beta adrenoceptors on the heart and kidney
What is the result of beta adrenoceptor antagonists?
reduced heart rate, reduced heart contractility, reduced renin release (reduces blood volume and TPR)
How do different beta adrenoceptor antagonists vary?
Different selectivity for beta 1 or beta 2 receptors, different sympathomimetic activity, different lipid solubility
What are the adverse effects of beta adrenoceptor antagonists?
cold extremities, fatigue, dreams, insomnia, bronchoconstriction
Why do beta blockers cause cold extremities?
because of reflex alpha-1 arenoceptor constriction and blockade of dilatory beta-2 adrenoceptors
Why do beta blockers cause fatigue?
reduced cardiac response and beta 2 blockade of skeletal muscle blood vessels
Why do beta blockers causes dreams and insomnia?
Depends on lipid solubility and whether they can pass the blood brain barrier
Why do beta blockers cause bronchoconstriction?
Because of beta-2 adrenoceptor blockade in airway smooth muscle
What are the contraindications for beta blockers?
diabetes, asthma, atrioventricular block (and care with heart failure and metabolic syndrome)
What are the names of calcium channel blockers?
verapamil, diltiazem, felodipine, nifedepine
What is the action of calcium channel blockers?
inhibits voltage gated L-type calcium channels in myocardium and vasculature
What is the result of calcium channel blockers?
reduces cardiac and vascular muscle contractility
What is the difference between the calcium channel blockers?
different selectivity for cardiac or vascular muscle - verapamil effects both, diltiazem is more selective for vascular muscle and felodipine and nifedepine are completely selective for vascular muscle
What are the adverse effects of verapamil and diltiazem?
oedema, flushing, headache, bradycardia
What are the adverse effects of felodipine and nifedepine?
oedema, flushing, headache, reflex tachycardia
What are the actions of thiazide diuretics?
inhibits sodium/cholride cotransporter in distal tubule to decrease sodium cholride reabsorption
What is the result of thiazide diuretics?
increases water and sodium excretion to lower blood volume and decrease blood pressure
What are the adverse effects of thiazide diuretics?
potassium loss, gout, hyperglycaemia, allergic reaction
