Drugs Flashcards
By binding to and inhibiting this transporter, digitalis causes the intracellular [Na+] to rise. An increase in intracellular sodium content reduces Ca++ extrusion from the cell via the Na+/Ca++ exchanger. Consequently, more Ca++ is pumped into the sarcoplasmic reticulum, and when subsequent action potentials excite the cell, a greater-than-normal amount of Ca++ is released to the myofilaments, thereby enhancing the force of contraction.
Digixon
The major therapeutic electrical effect of digoxin occurs at the
AV node.
Digixon modifies autonomic nervous system output by enhancing vagal tone and reducing ___ activity. As a result, digitalis decreases the frequency of transmission of atrial impulses through the AV node.
sympathetic
It is not beneficial in forms of heart failure associated with normal ven- tricular contractility (i.e., heart failure with preserved ejection fraction).
Digixon
Many factors contribute to digitalis intoxication, the most common of which is ___, often caused by concurrent administration of diuretics. ____ exacerbates digitalis toxicity because it further inhibits Na+K+-ATPase.
hypokalemia
At low dosages, less than 2 μg/kg/min, dopamine interacts primarily with dopaminergic receptors distributed in the renal and mesenteric vascular beds. Stimulation of these receptors causes local vasodilation and increases renal blood flow and glomerular filtration, facilitating diuresis
Dopamine
Medium dosages of dopamine, 2 to 10 μg/kg/min, increase inotropy directly by stimulating cardiac β1-receptors
These actions increase heart rate, cardiac contractility, and stroke volume, all of which augment CO.
High-dose dopamine is indicated in ____. However, these doses are inappropriate in most patients with cardiac failure because the peripheral vasoconstriction increases the resistance against which the heart contracts (i.e., higher afterload), which could impair left ventricular output.
hypotensive states such as shock
____ is a synthetic analog of dopamine that stimulates β1-, β2-, and α-receptors. It increases cardiac contractility by virtue of the β1 effect but does not increase peripheral resistance because of the balance between α-mediated vasoconstriction and β2-mediated vaso- dilation
Dobutamine
Like dopamine, it is useful for short-term therapy (less than 1 week), after which time it loses its efficacy, presumably because of down-regulation of adrenergic receptors. The major adverse effect is the provocation of tachyarrhythmias
Dobutamine
Unlike norepinephrine and epinephrine, it is a “pure” β-agonist, having activity almost exclusively at β1- and β2-receptors, with almost no α-receptor effect. In the heart, ___ has positive inotropic and chronotropic effects, thereby increasing CO.
isoproterenol
____ is sometimes used in emergency circumstances to increase the heart rate in patients with bradycardia or heart block
Isoproterenol
____ should be avoided in patients with myocardial ischemia, in whom the increased heart rate and ino- tropic stimulation would further increase myocardial oxygen consumption.
Isoproterenol
___ displays the electrophysiologic effects inherent to class IA agents but also has anticholinergic properties that may augment conduction at the AV node, thus antagonizing its direct suppressant effect.
Quinidine
prolongs QT, widens QRS
Cinchonism refers to CNS toxicity by ____ manifested by tinnitus, confusion, hearing loss, and visual disturbances. Quinidine can cause excessive prolongation of the QT interval, which may lead to torsades de pointes.
quinidine
____ has similar electrophysiologic effects as quinidine, though it does not prolong the action potential (and therefore QT interval) as much.
Procainamide
____ has mild ganglionic blocking effects that may cause peripheral vasodilation and a negative cardiac inotropic effect.
Procainamide
______’s electrophysiologic and antiarrhythmic effects are similar to those of quini- dine, but it has a greater anticholinergic effect. More so than quinidine or procainamide, _____ also has a pronounced negative inotropic effect and must be used with caution in patients with left ventricular systolic dysfunction.
Disopyramide
Digoxin is not beneficial in forms of heart failure associated with normal ventricular contractility (i.e., heart failure with preserved ejection fraction).
Although no longer a mainstay of therapy in heart failure, digitalis is sometimes useful in treating patients with heart failure complicated by
atrial fibrillation
The treatment of digitalis-induced tachyarrhythmias may include administration of potassium (if hypokalemia is present), intravenous ____ for bradyarrhythmias, or lidocaine (discussed later in the chapter) for ventricular ectopy
atropine
Milrinone, a nondigitalis, noncatecholamine agent, exerts its positive inotropic actions by inhibiting phosphodiesterase type 3 in cardiac myocytes.
Milrinone is sometimes used in the treatment of acute heart failure when there has been insufficient improvement with conventional vasodilators, inotropic agents, and diuretics. It has the potential for serious adverse effects, including provocation of ventricular arrhythmias, and chronic milrinone therapy is associated with ___ mortality. Its use is therefore lim- ited to hospitalized patients for short-term therapy.
increased
_____ has proved useful for maintaining blood pressure in patients with vasodilatory shock, as may occur in sepsis. It may also be beneficial during advanced life support for cardiac arrest because it increases coronary perfusion pres- sure, augments blood flow to vital organs, and improves the likelihood of successful resuscitation in patients with ventricular fibrillation.
Vasopressin
____ is an intravenous direct thrombin inhibitor, which is equivalent to UFH plus a GP IIb/IIIa inhibitor in preventing adverse ischemic outcomes, with less associated bleeding, in patients with UA or NSTEMI treated with an early invasive strategy.
Bivalirudin
In clinical trials in patients with UA or NSTEMI, the LMWH ____ has demonstrated reduced death and ischemic event rates compared with UFH.
enoxaparin
