Pharm - Hypertension Flashcards
What are the main drug classes used for HTN treatment
ACE inhibitors
Calcium channel blockers
Thiazide or thiazide like diuretics
Angiotensin receptor blockers
What are ACEi examples
Ramipril
Lisinopril
Perindopril
What are CCB examples
Amlodipine
Felodipine
What are thiazide diuretic example
Bendro-flumethiazide
What is a thiazide like diuretic example
Indapamide
What are ARB examples
Losartan
Irbesartan
Candesartan
What is the drug target for ACEi
Angiotensin converting enzyme
What is the drug target for CCB
L-type calcium channel
What is the drug target for thiazide like diuretics
Sodium/chloride co transporter
What is the drug target for ARBs
Angiotensin receptor
What is the main effect of ACEi
Prevents conversion of angiotensin 1 to 2 by blocking ACE.
Angiotensin 2 is a vasoconstrictor and stimulates aldosterone secretion which in turn increases blood volume thus pressure
What is the main effect of CCB
Block L-type calcium channels – predominantly on vascular smooth muscle. This results in a decrease in calcium influx, with downstream inhibition of myosin light chain kinase and prevention of cross-bridge formation. The resultant vasodilation reduces peripheral resistance.
What is the main effect of thiazide like diuretics
They block the Na+, Cl- co-transporter in the early DCT.
Therefore Na+ and Cl- reabsorption is inhibited.
As a result the osmolarity of the tubular fluid increases, decreasing the osmotic gradient for water reabsorption in the collecting duct.
What is the main effect of ARBs
These agents act as insurmountable (i.e. non-competitive) antagonists at AT1 receptor (found on kidneys and on the vasculature)
What are the main side effects of ACEi
Cough (due to bradykinin build up)
Hypotension
HyperK (take care with K sparing diuretics or K supplements)
Foetal injury
Renal failure (in patients with renal artery stenosis)
Urticaria/ angioedema
What are the main side effects of CCB
Ankle oedema
Constipation
Palpitations
Flushing/headaches
What are the main side effects of thiazide diuretics
HypoK
HypoNa
Metabolic alkalosis (increased H excretion)
HyperCa
hyperglycaemia (due to hyper polarised pancreatic beta cells)
Hyperuricemia
What are the main side effects of ARBs
Hypotension
HyperK (take care with K sparing diuretics or K supplements)
Foetal injury
Renal failure (in patients with renal artery stenosis)
Who is contraindicated for ARB or ACEi use
Pregnant women
What do ACEis require to work
Hepatic activation to generate active metabolites as they are pro drugs - therefore avoid in people with liver problems
What must we check regularly with ACEi
eGFR and serum K
Which is more effective: ACEI or ARB?
ACEi
What else should we know about CCB
Dihydropiridine type calcium channel blockers demonstrate a higher degree of vascular selectivity
How long do the diuretic effects of thiazide diuretics last
1-2 weeks of treatment
What explains the anti-hypertensive effect of thiazide drugs after a few weeks? In which drugs are these effects more pronounced
Due to the vasodilation properties - more pronounced in thiazide like diuretics
What ARBs are pro-drugs
losartan
Candesartan
What is clearance
The measure of the ability of the body to eliminate a drug - may occur as a result of processes in the liver, kidney and other organs
What is elimination half life
The length of time for the conc of a particular drug to decrease to half of its starting dose in the body
What are time to peak plasma levels
Time required for a drug to reach peak conc in the plasma - faster absorption leads to a lower time.
Why is it important that Indapamide and there thiazide like diuretics are excreted unchanged in the urine
This means that they are not metabolised therefore have an increased effect on the DCT.
