cardiovascular drugs Flashcards
what are arteriodilators
- work on systemic and pulmonary arterioles to decrease afterload
- decreasing afterload in dogs with DCM and mitral regurgitation(MR) can help improve cardiac output
- hydralazine, ca channel blockers, nitroprusside, ACEI
what is an example of a venous dilator
nitroglycerine
what are examples of balanced vasodilators
- ACE inhibitors
- nitrates (nitroprusside)
what are examples of arteriodilators
- amlodipine
- hydralazine
what is angiotensin II
important detrimental hormone in animals with heart dx
what does angiotensin II do
- fluid and Na retention
- vasoconstriction
- increased thirst
- vascular and myocardial fibrosis and pathologic tissue remodeling
- increases aldosterone
what do ACEI do/are
- balanced vasodilators
- reduce aldosterone release, so reduced Na & H2O retention
- prevent angiotensin II mediated myocardial fibrosis and remodeling
- general anti-adrenergic effects
- reduce vasopressin release (ADH)
- reduce endothelin release
- prevent glomerular capillary hypertension
- reduce the metabolism of angiotensin 1-7 and bradykinin, both of which promote vasodilation and natriuresis
RAAS blockade
____ and ____ is recommended for dogs with CHF
ACEIs and spironolactone
concurrent administration of an ACEI and spironolactone helps prevent or manage:
hypokalemia in patients treated with loop diuretics
how are benazepril and enalapril excreted
- benazepril: eliminated through hepatic and renal mechanisms
- enalapril: renally eliminated
what is the most effect drug for inhibition of serum angiotensin-converting enzyme activity in horses
benazepril
what are the guidelines for monitoring ACEI
- biochemical variables (1-2wks after initiation of therapy)
- ACEIs can cause hyperkalemia (infrequently)
- a small rise in serum creatinine is expected after ACEI initiation
- blood pressure monitoring should ideally be performed at each recheck
what is semintra
- management of feline hypertension
- only FDA-approved tx for feline hypertension in an easy-to-give formula
what are the actions of nitrates
- venous vasodilaton: increase venous capacitance (reduce preload)
- arterial vasodilation (at high doses, reduce afterload)
what are the 3 major nitrates used
- nitroglycerin
- isosorbide (mono, di-) nitrate
- nitroprusside
what is the mechanism of action of nitrates and tolerance
- co-administration of n-acetylcystine which donates - SH
- staggered therapy
- several days of administration followed by several days off therapy
how do arterioldilators work
reduce myocardial work-load
- can reduce systemic blood pressure but not compromise organ perfusion
- reduces afterlooad, and myocardial wall stress, so reduces myocardial oxygen consumption
- unloads the failing heart
what is IV nitroprusside
- converted directly into NO w/o involvement of -SH groups & therefore tolerance does not develop
- potent balanced vasodilation: both an arteriodilator as well as a venodilator
- very short half-life and administered as CRI
- toxicity high in dogs
what are the indications to use IV nitroprusside
refractory CHF
what are the adverse effects of using IV nitroprusside
- hypotension
- reflex tachycardia
what are the two different classes of Ca channel blockers
- dihydropyridines
- non-dihyrdropyridines
what are non-dihydropyridines
cardiac > vascular effects
verapamil and diltiazem
what are the dihydropyridines
amlodipine and nicardipine
what are the characteristics of DHP CCB
- long duration of action
- vascular»_space; mycardial action
- used to tx systemic hypertension
- almost no effect on HR or inotropic state
what is an ex of a phoshodiesterase inhibitor
pimobendan (balanced vasodilator)
what is an example of a NaKATPase inhibitor
digoxin
what are ex of sympathomimetics (beta receptor agonists)
dopamine, dobitamine
how does pimobendan work
it is an inodilator
- has both positive inotropic and vasodilatory effects
- increased sensitization of the cardiomyocyte to Ca - leads to increased contractility (inotropy), and inhibition of phosphodiesterase 3 & 5 enyzmes
- leads to smooth muscle relaxation
- both increased contractility and afterload reduction, increases stroke volume and cardiac output
what is the EPIC trial
- pimobendan with dogs with CVD
- delays the onset of CHF by approx. 15 moonths in dogs with preclinical DMVD compared to placebo
what is digoxin
- negative chronotrope
- weak positive inotrope
- favorable autonomic effects
- normalizes baroreceptors
- narrow therapeutic window and easy to cause toxicity
what are the indications for digoxin
primarily rate control atrial fibrillation
what are toxicity signs with digoxin
- cardiac arrhythmias
- GI
- neurological
what are sympathomimetics
- mimic effect of native sympathetic transmitters (NE, E)
- bind to cardiac beta-adrenergic receptors
- activate cAMP -> protein phosphorylation -> increased Ca-actin/myocin binding
- extensive first pass metabolism, short half lives (1-2 min)
- given IV constant infusion
what is dopamine
beta 1 and alpha 1 agonist
- precursor of norepinephrine
- binds to B-receptors (heart: increase heart rate and contractility)
- binds to dopaminergic receptors (renal, mesenteric vessels, causing vasodilation)
- dose dependent effects (high doses cause tachycardia and can also bind to a-adrenergic receptors causing vasoconstriction, excessive tachycardia)
what is dobutamine
beta 1 agonist primarily
- synthetic catecholamine
- stimulates b1 receptors strongly, peripheral b2 and alpha 1 receptors weakly
- used for acute phase support of low cardiac output and myocardial failure
is dopamine a vasopressor
yes
is dobutamine a vasopressor
no
