pharmacology of hypertension Flashcards
ACEi examples
Ramipril
Lisinopril
Perindopril
mechanism of action of ACEi
nhibit the angiotensin converting
enzyme.
Prevent the conversion of
angiotensin I to angiotensin II
by ACE.
What must be carefully monitored when prescribing ACEi
eGFR and serum potassium
6 side effects of ACEi
1) cough
2) hypotension
3) hyperkalaemia (be careful with potassium supplements and potassium sparing diuretics)
4) foetal injury (don’t give to pregnany women)
5) renal failure (in renal artery stenosis)
6) urticario or angioedema
What do ACE inhibitors need to have a therapeutic effect and why
Most ACEi are pro drugs so need hepatic activation to generate active metabolites needed for therapeutic effect
Mechanism of action of calcium channel blockers
Blocks L type calcium channels mostly on vascular smooth muscle. Decreased influx of calcium causes inhibition of myosin light chain kinase and prevention of cross bridge formation. So vasodilation occurs decreasing peripheral vascular resistance
Target of calcium channel blockers
L type calcium channels
Ex of calcium channel blockers
amlodipine. felodipine
side effects of calcium channel blockers
ankle oedema
constipation
palpitations
flushing or headaches
Dihydropyridine type calcium channel blockers demonstrate a higher degree of vascular selectivity
yes
Which diuretics cause hypercalcaemia
thiazide diuretics
Mechanism of action of thiazide diuretics
Blocks Sodium chloride co transporters in early DCT. so sodium and chloride reabsorption is blocked
This increases osmolality in the tubular fluid, decreasing the osmatic gradient in the collecting duct for water reabsorption
Side effects of thiazide diuretics
hypokalaemia hyponatraemia hypercalcaemia hyperuricaemia hyperglycaemia (hyperpolarised pancreatic beta cells)
Ex of thiazide diuretic
bendro -flu-methiazide
Ex of thiazide like diuretic
indapamide
Thiazide and thiazide-like diuretics both lose their diuretic effects within 1-2 weeks of treatment.
Thiazide and thiazide-like diuretics both lose their diuretic effects within 1-2 weeks of treatment.
Why do thiazides still retain anti hypertensive properties after losing their diuretic effect
Continuing anti-hypertensive action appears to be due to vasodilating properties (these are more pronounced for the thiazide-like diuretics)
Ex of ARBs
Losartan
Irbesartan
Candesartan
ARB mechanism of action
non competitive antagonist at AT1 receptor (on kidneys and vasculature)
Side effects of ARBs
hypotension
hyperkalaemia (N.B k sparing diuretics and supplements)
foetal injury (don’t give to pregnants)
renal failure (if renal artery stenosis)
Are ARBs or ACEi more effective
Most trials indicate that angiotensin receptor blockers are not as effective anti-hypertensive agents as ACE inhibitors.
Losartan and candesartan are what type of drugs
Losartan and candesartan are pro-drugs. They require hepatic activation to generate the active metabolites required for therapeutic effects.
Def clearance
Clearance is the measure of the ability of the body to eliminate a drug. Clearance by means of various organs of elimination is additive. Elimination of drug may occur as a result of processes that occur in the liver, kidney, and other organs
Def elimination half life
Elimination half-life is the length of time required for the concentration of a particular drug to decreasetohalf of itsstarting dose in the body.
Def time to peak plasma levels
Time to peak concentration is the time required for a drug to reach peak concentration in plasma. The faster the absorption rate, the lower is the time to peak plasma concentration.
Explain would you see reflex tachycardia in amlodipine or felodipine
amlodipine has a longer half life and a slower onset so you don’t get the reflex tachycardia that you see in felodipine
compare felodipine and amplodipine in terms of elimination, and time to reach peak plasma levels
felodipine reaches peak plasma levels quicker and is eliminated quicker
