Vasodilators and Sympatholytics DSA I Flashcards
vasodilators
relax smooth m of arterioles
- decreased TPR
- symapthetic reflex prevents orthostatic hypotension and sex dysfunction
- vasodilators work best with other anti-hypertensives
DHPs
block vascular L-type Ca channels > cardiac
CCB
non-DHPs
non-selective block of vascular and cardiac L-type Ca channels
CCB
CCBs
smooth m. - vasodilation arterioles > veins
-decreased TPR, afterload, O2 heart demand
cardiac muscle - reduced contractility, slowed SA node pacemaker and AV node conduction velocity**
CCB pharmacy
oral admin
- high first pass
- often used IV
amlodipine
long half life CCB
adverse effects for DHP CCBs
excessive hypotension, dizzy, HA, periphera edema, flushing, tachycardia, rash, gingival hyperplasia
adverse effects for non-DHP CCBs
dizzy, HA, peripheral edema, constipation, AV block, bradycardia, heart failure, rash with diltiazem, pulmonary edema, coughing, wheezing
short acting nifedipine
studies indicate - increasead risk of MI, stroke, death
-not for chronic HTN
instead use slow-release and long-acting DHPs
non-DHP contraindication
beta-blocker use
AV conduction
nifedipine does not decrease AV conduction
-therefore, use more safe in AV conduction abnormalities
verapamil
may increase digoxin levels
clinical use of CCBs
long term therapy for HTN, HTN emergency, angina
K channel openers
open K channels in smooth m.
- hyperpolarizes smooth m. membrane
- reducing probability of contraction
- arteriolar dilator - reduced systemic vascular resistance and MAP
diazoxide
potassium channel opener
- long acting
- high protein binding
- administered 3-4 injectsions 5-15 min apart
potassium channel opener adverse effects
hypotension - stroke and MI
- hypotension greater with renal failure patients, patients with beta-blockers (give small doses)
- hyperglycemia
- avoid ischemic heart disease (likely angina)
potassium channel opener use
hypertensive emergency
minoxidil
potassium channel opener in smooth m.
-dilation of arterioles, not veins
adverse effects of minoxidil
HA, sweating, hypertrichosis (hair growth)
must be used in combo with beta blocker and loop diuretic
-bc of reflex sympathetic stimulation and sodium/fluid retention (angina, edema, palpitations, tachycardia)
clinical use of minoxidil
long term outpatient for severe HTN
stimulate hair growth
minoxidil - rogaine
fenoldopam
dopamine D1 agonist
- peripheral arteriolar dilator and natriuretic
- administered IV (short half life and rapid metabolism)
- avoid in glaucoma patients
post-operative HTN
fenoldopam
hydralazine
stimulates NO release from endothelium
- increased cGMP
- dilation of arterioles
- high first pass - low bioavailabilty
adverse with hydralazine
HA, nausea, anorexia, palpitations, sweating, flushing
-angina or arrhythmia in ischemic heart disease
hydralazine clinical use
long term outpatient HTN
-combo with nitrates - heart failure and HTN in blacks
HTN in pregnancy Tx
methyldopa and hydralazine
sodium nitroprusside
releases NO > increased cGMP
-dilation of arterial and venous vessels
-BP decrease and CO same
IV admin
cyanide poisoning
released during metabolism of sodium nitroprusside
nitroglycerin
release NO
- relax smooth m of veins > arteries
- no effect on cardiac/skeletal m
- decreased platelet aggregation
high first past - administer sublingual
reached minutes, last 15-30 minutes
-longer duration patches available
adverse effects of nitroglycerin
orthostatic hypotension, syncope, throbbing HA
contraindicated - increased intracranial pressure
drug-drug nitroglycerin interactions
synergistic hypotension
-wth sildenafil, tadalafil, or vardenafil
