cards long list Flashcards
carvedilol
non selective beta blocker with alpha 1 activity
especially useful for congestive heart failure
moderate lipid solubility
eliminated by liver
labetolol is another combination blocker
metoprolol
beta 1 selective beta blocker
with moderate lipid solubility
eliminated by liver
propranolol
non selective beta blocker
high lipid solubility
eliminated by liver
atenolol
beta 1 selective beta blocker
low lipid soluble
eliminated by kidney
longer action –> can be dosed once daily
class II antiarrhtyhmic
atropine
parasympathetic antagonist (muscarinic) competitive antagonist
blocks vagal response
might stop AV block –> for ex inferior wall MI or dig toxicity
almost no CNS effect at clinical doses
given by IV
procainamide
class Ia antiarrhythmic
tragets Ina and Ik
depresses fast response excitability and increases APD
lidocaine
class Ib antiarrhythmic
Targets Ina
depresses fast response excitability especially in depolarized tissue
*not useful at normal resting potential
flecainide
class Ic antiarrhythmic
depress fast response excitability in noemal and depolarized tissue
dofetilide
class III antiarrhythmic
targets Ik
prolong APD without depressing excitability in fast response tissue
verapamil
Ca cahannel blocker
Ica targeted
depress conduction and excitability in slow response tissue (AV node, SA node)
effective in tx of paroxysmal SVT and tx of angine (decrease myocardial o2 demand and increase coronary blood flow) & tx htn (reduce SVR)
*notable side effect is constipation
what are class I and III antiarrhythmics used for
vent tachy
atrial fib
AV reentry
what are class IV antiarrhythmics, digoxin and adenosine used for
AVNRT
what is unique about class Ia antiarrhythmic
also blocks Ik so increased action potential duration
factors that modify the strength of sodium channel blockade
Ib< IA< IC
resting membrane potential - more potent when more negative
hear rate - more potent at faster heart rate
factors that increase the effect of Ik blockade on APD
slow hear rates
low extracellular K
low extracellular M
effect of digoxin in arrhythmia
enhance vagal by increasing muscarinic receptor
decress I ca and increase I K ach
*only drug that acts on slow response tissue that is a positive inotrope
slow onset of effect and duration greater than 1 day!
adenosine
adenosine receptor agonist
decrease calcium current and icnrease potassium current from ach
onset of action and duration of effect is seconds!!
what is major determinant of ERP in fast and slow response tissue?
fast - APD
slow- recovery of ca channel
selectivity of calcium channel blockers
verapamil - cardiac
nifedipine - vascular
diltiazem cardiac and vascular
how to tx afib
1) slow AV node -> atenolol, digoxin, verapamil
2) stop fibrillation in atrial muscle –> procainamide, amiodarone, sotalol, dofetilide, dlecainide
conditions that raise risk of using antiarrhythmic drugs
prolonged QT esp with low K, Mg
sick sinus node
AV block
poor systolic fx
prazosin
alpha 1 & alpha 2 antagonist - alpha 1 more than alpha 2
used to decrease peripheral vascular resistance
primary used in tx of htn (third line)
improves voiding in pts with urinary bladder outlet obstruction
postural hypotension may occur
alpha adrenergic antagonists
prazosin, doxazosin, terazosin
zosin endings!
Doxa and tera are pura alpha 1 blockers
doxa and tera are slower onset and longer duration
beta adrenergic antagonists
propranolol, metoprolol, atenolol, carvedilol
distinguished by beta 1 selectivity,
instrinsice sympathomimetic activity,
lipid solubility
duration of action
atenolol- hydrophilic- metabolized by kidney
ends for sympathetic antagonists & ace inhibitors
beta antagonists - end with olol or ilol
alpha ends with zosin
ace inhibitor - pril
selectivity of beta blockers
propranolol - beta 1 & 2 - nonselective
metoprolol & atenolol - beta 1 selective
carvedilol - non-selective with alpha 1 blockade!
how are beta blockers used in CV medicine
decrease HR, decrease impulse conduction, decrease cardiac contractility and metabolic rate
used in heart failure, MY/angina, arrhythmias, htn
beenfits of beta blockade in tx of ischemia
improve myocardial o2 supply –> decrease hr which prolongs diastole, improves subendocardial perfusion
decrease myocardial o2 demand –> suppresses HR & contractility, blocks sympathetic reflex, reduces double product, helps reduce BP
losartan
first synthetic antagonist to AT1 receptor
potentially used to correct aortic phenotype of marfans syndrome
improves aortic dilatation in severely affect children
name ace inhibitors
captopril
enalapril
lisinopril
rampipril
limitations of ace inhibitors
non specific enzyme
alternate pathways for ang II
poor side effect profile - cough and rare angioedema
other enzymes that can make ang II
CAGE
cathepsin G
chymase
from angiotensinogen –> angII
t-Pa
cathepsin G
tonin
arbs
block AT1
downstream from alternative angII pathway
no build up of bradykinin (good & bad)
AT2 receptors still are able to be acivated
direct renin inhibitor
inhibits renin at pt of activation by binding to renin
increases plasma renin concentration
reduces production of angI, angIII and PRA
less potent than acei and arbs are monotherapy
aliskiren - $$
thiazide
diuretic acts at distal convoluted tubule by binding to NaCl cotransporter and reducing Na absorption
reduces blood volume and decreases CO and BP
compensatory mechanisms counteract the acute effects LT (renin and aldosterone)
variable degree of adaptation
mechanism of LT action mystery –> proposed decrease in PVR secondary to increased NO production
long duration fo action (24 hours)
toxicities of thiazide diuretics
sulfa allergy
hypokalemia
promote insulin resistance
increase TG and LDL cholesterol
two classes of calcium channel antagonists
1) non dihydropyridine –> verapamil, diltiazem
2) dihydropyridines–> nifedipine, amlodipine
non-dihydro- bind while channel is open –> more effective in tissue that is frequently stimulated
dihyrdo- bind during resting state
diltiazem
non dihydropyridine CCA –> lowest incidence of SE and effective in tx SVT
not great htn drug
nifedipine
CCA that is primarily peripheral vasodilatory effects
effective for atn
contraindicated in post MI, CNF bc fine balance of o2 demand –> result in increase hr because of profound decrease in PVR
side effects - facial flushing, headaches, dizziness, palpitations
most commonly prescribed anti htn drug as monotherapy
direct peripheral vasodilators
venous - nitrates
arterial hydralazine, minoxidil
both arterial and venous - nitroprusside
don_t share common MOA
use second drug to block compensatory mech (beta blocker often)
hydralazine
unknown moa
direct arteriolar dilation with no effect on veins
preferentially effects renal, peripheral, splanchnic and coronary arteirs
descrease in pvr –> decrease BP
SE - flushing, sweating, palpitations, hypotension, angina
**phase 2 metabolism –> acetylation
**limited use - hypertension during pregnancy including preeclampsia
usually used in combo with b antagonist
minoxidil
direct vasodilator that activates atp-modulated K[ channel in arteris allowing k+ to leave cell cause hyperpolarization and relaxation
direct arteriolar vaso without effect on veins
decrease in pvr –> lower bp
use with b blockers and diuretics to stop compensatory mech
sodium nitroprusside
MOA - metabolized by smc into NO –> activates guanylate cyclase –> c-GMP which produces SMC relaxation and vaso
-both arterioles and veins –> decrease pre and after load
*rapid metabolized in rbcs in to cyanide which is metabolized by rhodanase in mito to thiocyanate
dosium thiosulfate, cofact for shodanase, is added to solution prior to administration to prevent cyanide tox
unstable in direct sunlight
**used for htn emergencies - rapid onset 1 - 2 minutes and everyone responds
initiate therapy with b blocker before discontinuing infusion