Definition of hypertensive
a sustained systolic BP >140mmHg or sustained diastolic BP >90mmHg
Causes of hypertension
Pre-existing condition
Genetic factors
Low birth weight/premature birth
Environmental factors eg. smoking, stress, diet, alcohol
Diabetes
Drugs eg. steroids, MAOIs, caffeine, aspirin
Kidney/ CV disease
ACE inhibitors
Low BP causes the enzyme renin to catalyse the reaction of angiotensin –> angiotensin 1 –> (ACE enzyme causes) angiotensin 2 –> vasoconstriction and aldosterone secretion
ACE inhibitors block angiotensin converting enzymes, causing vasodilation (bradykinin) and reduced peripheral resistance
Side effects: persistent cough (bradykinin causes spasmogenic actions on bronchial smooth muscle), rash, renal problems, hypotension, don’t use in pregnancy
eg. captopril, enalapril, Ramipril, usinopril
Angiotensin receptor antagonists
Selectively block angiotensin 1 receptors to cause vasodilation
Side effects: dizziness and hyperkalaemia
eg. losartan, candesartan, valsartan
Beta-blockers
Sympathetic nerves act on B-receptors to decrease cardiac output
Renal sympathetic nerves act on B-receptors to decrease renin release
Acts on vasomotor centre in medulla to decrease sympathetically mediated vasoconstriction
Acts on beta 1 and 2 adrenoreceptors, blocks the action of adrenaline and noradrenaline, reduces heart rate, blocks vasoconstriction, increases blood flow to the kidneys to decrease renin secretion
Side effects: legarthy, achy limbs, aggravation of asthma
eg. atenolol, labetalol (used in pregnancy)
Alpha blockers
used less
Block action of noradrenaline and adrenaline on blood vessels causing vasodilation
Side effects: postural hypotension
eg. prazosin, doxazocin
Calcium channel blockers
Dilate arteries
Reduce contractility and/or heart rate
eg. nifedipine, amlodipine - more potent on blood vessels, but may cause dizziness and headaches
eg. verapamil, diltiazem - more potent on the heart rather than blood vessels, cause constipation heart block
Thiazide and thiazide-like diuretics
These acts on the kidneys to increase urine production, which lowers blood volume therefore lowering BP
Side effects: hypokalaemia, decrease insulin release, increase plasma lipids and urate = gout
eg. indapamide, chlortalidone, bendroflumethiazide
Potassium-sparing diuretics
Given alongside thiazide diuretics to spare/protect potassium levels
eg amiloride, spironolactone
Loop diuretics
Drugs act on the Loop of Henle to inhibit sodium reabsorption
Used to treat severe hypotension
Side effects: can affect hearing, hypokalaemia
eg. furosemide
Other vasodilators
Cause relaxation of the smooth muscle in blood vessels
eg. Hydrazilline - non-selective K+ channel opener
eg. Minozidil - powerful vasodilator used in extreme hypertension
eg. Intravenous nitrates and sodium nitroprusside - both used in hospital emergencies