Extra CV Drugs Flashcards
Nipride uses:
First-line drug for treatment of hypertensive emergencies (d/t rapid reduction of arterial pressure by decreasing LV preload and afterload)
Useful for treatment of cardiogenic shock (b/c arterial vasodilation improves forward flow by reducing impedence to LV ejection while venodilation decreases LV filling pressures)
Used for patients with preeclampsia (prevents dangerous elevations in systemic and pulmonary artery BP during laryngoscopy).
Used in combo with a beta1-adrenergic antagonist (eg. esmolol) to decrease arterial pressure, depress myocardial contractility, and reduce ascending aortic wall stress in patients with acute aortic dissection until direct surgical control of the injury can be achieved.
Nipride metabolites:
The following accumulate with high doses or prolonged administration:
Cyanide –> binds with cytochrome C to inhibit aerobic metabolism and causes lactic acidosis
Also binds with hemoglobin to form methemoglobin, and with sulfur to for thiocyanate
(the latter may accumulate in patients with renal insufficiency and produce neurologic complications including delirium and seizures.)
Dobutamine uses:
Diagnostic tool for the detection of coronary artery disease (CAD)
Good for heart failure patients with elevated pulmonary vascular resistance and LV filling pressures.
Dobutamine adverse effects:
Dobutamine-induced pulmonary vasodilation has the potential to exacerbate ventilation-perfusion mismatch, increase transpulmonary shunt, and contribute to relative hypoxemia
Also, do no use for positive inotropic support in cardiac surgery for patients with LV dysfunction (adverse events have occured)
___ is the biochemical precursor of norepinephrine.
Dopamine
Nitroglycerine MOA:
organic nitrate that dilates venules to a greater degree than arterioles –> results in decreased myocardial oxygen demand by reducing LV preload, and to a lesser extent afterload, thereby producing corresponding reductions in LV end-diastolic and end-systolic wall stress.
Dobutamine:
higher infusion dose and effects
5 mcg/kg/min –> dobutamine (-) isomer progressively stimulates the alpha1-adrenoceptor; this mitigates the magnitude of vasodilations from beta2 activation and effectively preserves LV preload, afterload, and arterial pressure
Also serves to blunt the baroreceptor reflex-mediated tachycardia that might otherwise occur.
Dobutamine
MOA on receptors
Synhetic catecholamine that contains two stereoisomers (- and +), both of which stimulate beta-adrenoceptors, but they cause opposing agonist (-) and antagonist (+) effects on alpha1-adrenoceptors
As a result, dobutamine is a potent stimulator of beta-adrenoceptors but the drug has little effect on alpha1-adrenoceptors when administered at infusion rates less than 5 mcg/kg/min.
(Once administered at rate above 5 mcg/kg/min, (-) isomer progressively stimulates the alpha1-adrenoceptor)
Dopamine side effects:
tachycardia in cardiac surgery patients (epinephrine causes less)
increased LV afterload (an arterial vasodilator like, sodium nitroprusside, may be used to blunt this effect and further enhance cardiac output)
directly increases myocardial oxygen consumption and may cause or worsen myocardial ischemia in the presence of hemodynamically significant coronary stenoses.
Sodium nitroprusside (Nipride) MOA:
ultra-short-acting direct NO donor
NO stimulates guanylate cyclase within vascular smooth muscle cells to convert GTP to cGMP –> cGMP activates cGMP-dependent protein kinase that dephosphorylates myosin light chains and contributes to relaxation of vascular smooth muscle.
NO also stimulates Ca++ reuptake into the sarcoplasmic reticulum by activating the sarcoplasmic reticulum Ca++ ATPase. –> causes relaxation
NO also stimulates K+ efflux from the cell by activating K+ channel –>cellular hyperpolarization and relaxation
Nitroglycerin effects:
Improves the balance of myocardial oxygen supply to demand through its actions as a direct coronary vasodilator (increases supply) and its systemic hemodynamic effects (reduces demand)
dilates both normal and poststenotic epicardial coronary arteries, enhances blood flow through coronary collateral vessels, and preferentially improves subendocardial perfusion
also inhibits coronary vasospasm and dilates arterial conduits used during CABG surgery
Nitroglycerine uses:
first-line drug for the treatment of myocardial ischemia (use caution in pts with ischemia who are also hypovolemic because nitro might exacerbate hypotension and further compromise coronary perfusion/blood flow)
Dobutamine:
lower infusion dose and effects
5 mcg/kg/min –> potent stimulation of beta-adrenoceptors: enhances myocardial contractility (beta1 agonist) and simultaneously reduces arterial vasomotor tone (beta2 agonist)
These actions markedly improve LV-arterial coupling, enhance myocardial efficiency, and increase cardiac output in the presence or absence of LV dysfunction.
Dopamine:
Moderate doses (___) have what MOA and effect?
3-8 mcg/kg/min
alpha1; beta1 adrenergic agonist –> elevates arterial pressure and has positive inotropic effects (increased CO)
alpha1 activation –> arterial: increases LV afterload; venous: enhances venous return
beta1 activation –> increases myocardial contractility
Nipride C/I:
relatively C/I in patients with acute myocardial ischemia b/c it causes abnormal redistribution of coronary blood flow away from ischemic myocardium (“coronary steal”) (this is because nipride produces greater coronary vasodilation in vessels that perfuse normal myocardium compared with those that supply the ischemic territory)
renal insufficiency (d/t toxic metabolites that accumulate and produce neurologic complications including delirium and szrs.)
