hypertension 3 Flashcards
what are the two types of pharmacological therapy for hypertension?
1- Sympatholytic Agents
2- Directly-acting Vasodilators
what are the two types of sympatholytic agents?
a-Adrenoceptor Blocking Drugs
Centrally-acting Drugs
what are the 3 types of directly acting vasodilators?
Hydralazine
Minoxidil
Na nitroprusside
what is the main A- adrenoceptor blocker and whats its MOA?
block a-1-adrenoceptors in arterioles & venules and decrease PVR
what are the characteristics of the anti-hypertensive effect of A-adrenoceptor blockers?
fall in BP with associated -decrease TPR
little/no change in CO
orthostatic/postural hypotension
benefits of A-adrenoceptor blockers?
favourable effects on plasma lipid & glucose levels
equal efficacy in all age & racial groups
most beneficial in patients with benign prostatic hypertrophy (BPH)
what kind of therapy is A-adrenoceptor blocking drugs?
it is an add on therapy with BB and thiazide like diuretics- recommend for patients with resistant hypertension
what are the adverse effects of a-adrenoceptor blocking drugs?
first-dose hypotension & syncope
postural hypotension
dizziness, fatigue, drowsiness, headaches
fluid retention & tolerance
what are the 3 main centrally acting agents?
Clonidine
Moxonidine
a-Methyldopa
what agonist is clonidine selective for clonidine?
a2- adrenoceptor agonist
what is moxonidine selective for?
relatively selective a2-adrenoceptor & I1-imidazoline receptor agonist
what is a-methyldopa selective for?
converted to a-methylnoradrenaline
a1-adrenoceptor agonist
how do centrally acting agents produce their antihypertensive effect?
act centrally in lower brainstem/medullary vasomotor centre
a2-receptor activation -decrease sympathetic outflow to heart & blood vessels -decrease HR, CO & PVR -decrease BP
a2-receptor activation- increase cardiac vagal tone decrease HR and BP
are the efffects of metabolism & plasma lipids favourable or unfavourable in centrally acting agents?
favourable
what centrally acting agent is safe to use in pregnancy?
a-Methyldopa
what are the 4 side effects of centrally acting agents?
1-sedation, drowsiness, mental lassitude, dry mouth
2-rebound effect
3-Na & fluid retention ->pseudotolerance
4- hypersensitivity reactions –drug fever, hepatitis, haemolytic anaemia
what are the two oral directly acting vasodilators?
Hydralazine
Minoxidil
what is the parental directly acting vasodilators ?
Na nitroprusside
what directly acting vasodilator can be used for both oral and parenteral?
hydralazine
how do directly acting vasodilators produce their effect?
relaxation of blood vessels/dilation
decrease in TPR and cO
How does Na nitroprusside produce this antihypertensive effect?
increase intracellular cGMP - increase in relaxation
how does relaxation Minoxidil produce its antihypertensive effect?
open K+channels > hyperpolarization
what are the clinical uses for minoxidil and Hydralazine?
reserved for severe/refractory HPT
must be used in combination with diuretics & BBs
what are the clinical uses for Na nitroprusside?
reserved for severe hypertensive crisis/emergencies
what are the 3 adverse effects of directly acting vasodilators?
postural hypotension & fluid retention
reflex sympathetic stimulation- risk of angina
headaches, dizziness
when do you treat adults with hypertension?
Adults of any age with persistent Stage 2 HPT (BP >160/100 mmHg)
when do you treat adults under 80 with stage 1 hypertension?
when they also have one of the following: target organ damage existing / established CVD renal disease diabetes an estimated 10-year CVD risk >10%
when do you treat adults under 60 with stage one hpt?
when they have an estimated 10-year CVD risk <10%
when do you treat adults over 80 for hpt?
a clinic blood pressure of over 150/90
what are the clinical BP targets?
aim for target BP <140/90 mmHg in under 80 year olds
aim for target BP <150/90 mmHg in over 80 year olds
what are the BP targets for BPM or HBPM in addition in patients with ‘white coat effect’
aim for target BP <135/85 mmHg in under80 year olds
aim for target BP <145/85 mmHg in over80 year olds
what are the 3 types of drug therapy associated with hypertension treatment?
Initial Monotherapy with ‘Stepped-Care’ Approach
Initial Monotherapy with ‘Sequential Monotherapy’ Approach
Initial Combination Therapy (with SPC therapy)
what is initial monotherapy with stepped care approach?
start with lowest recommended dose of 1st-line drug(s)
titrate up …. till BP control achieved, treatment not tolerated or maximum dose reached (except some diuretics)add next recommended drug …….
allow >4 weeks to observe full response at each
what is combination therapy?
control of BP with two or more drugs
needed to achieve target BP levels in >60% of patients indicated for lower target BP levels & in high risk groups
what is a disadvantage of combination therapy?
one drug may inhibit activation of compensatory mechanisms by another drug
e.g. b-blocker & diuretic with vasodilator
ACEI with diuretic
additive /synergistic effect achieved with drugs acting on different mechanisms
e.g. diuretic with b-blocker/ACEI/a-blocker
