Primary hypertension & pharmacotherapeutics Flashcards
Primary hypertension typically presents as?
chronic, , progressive elevation in arterial blood pressure of unknown origin.
Aim of therapy is to reduce and maintain blood pressure to prescribed targets, which is achieved by
by reducing CO and / or TPR
What are the three factors involved in sustaining raised total peripheral resistance (TPR)?
Vasoconstriction
Arteriosclerosis
Rarefaction
What is Rarefaction?
loss of vessels in tissue
what do the RAAS inhibitors as a Peripherally acting antihypertensive drugs do?
reduce CO (via decreasing preload) and TPR (via arterial vasodilation)
How is Vascular resistance calculated?
Resistance is proportional to 1/blood vessel radius4
what do the Peripherally acting antihypertensive drugs do
RAAS inhibitors e.g. lisinopril, irbesartan, aliskiren, spironolactone
reduce CO (via decreasing preload) and TPR (via arterial vasodilation)
Thiazide-like diuretics e.g. indapamide
reduce CO and TPR (act as vasodilators)
ß1-adrenoceptor antagonists e.g. atenolol
reduce CO (via decreasing heart rate and inotropy) (acutely) then TPR (via arterial vasodilation) (chronically)
Calcium channel blockers (CCBs)
dihydropyridines (vasoselective)
e.g. amlodipine, nifedipine, nicardipine, felodipine
mainly reduce TPR (via arterial vasodilation)
non-dihydropyridines (cardioselective/non-selective)
e.g. verapamil, diltiazem
reduce TPR and CO (via decreasing heart rate and inotropy)
1-Adrenoceptor antagonists e.g. prazosin
reduce TPR (via arterial vasodilation)
Directly acting vasodilators e.g. hydralazine, minoxidil
reduce TPR (via arterial vasodilation)
What are the two theories of causation?
Neurogenic theory
Renal salt balance theory
What is Neurogenic theory?
Overactivity of sympathetic nervous system
involves NA and Ad actions to raise both cardiac output (CO) and total peripheral resistance (TPR) (via vasoconstriction, i.e. decrease in peripheral blood vessel radius)
What is Renal salt balance theory
Salt intake exceeds renal salt excretion
ANP is released in response to increased blood volume, which chronically leads to rise in TPR (via vasoconstriction)
How do you calculate blood pressure?
Blood pressure (BP) = CO * TPR
How does arteriosclerosis cause TPR?
Reductions in the blood vessel lumen diameter caused by medial wall hypertrophy and thickening related to arteriosclerosis.
How does endothelial dysfunction contribute to raised TPR?
loss of endothelium-derived vasodilators e.g. nitric oxide (NO), PGI2
increased release of vasoconstrictors e.g. ET-1
Name two vasodilators?
nitric oxide (NO) prostacyclin (PGI2)
what do the Thiazide-like diuretics as a Peripherally acting antihypertensive drugs do?
reduce CO and TPR (act as vasodilators)
