Miscellaneous drugs Flashcards
Miscellaneous antiarrhythmic drugs - 4 drugs
Adenosine
Digoxin
Magnesium sulfate
Ivabradine
Adenosine - MOA
Activates G protein-coupled adenosine receptors. This further activates ACh-sensitive K channels and block Ca influx in SA node, atrium and AV node.
Adenosine - effects
Cell hyperpolarization slows the AV node conduction velocity, and increases the AV node refractory period.
AV node conduction can be completely blocked for a few seconds.
Adenosine - adm and duration of action
Rapid IV bolus. Half-life is 10 seconds.
Digoxin - MOA as antiarrhythmic
Indirect increment of vagal tone.
Digoxin - effects
Slow the AV node conduction velocity & increase its refractory period.
Positive inotropic effect.
Digoxin - indicaitons
Heart failure.
Slow ventricular rate in AF (not preferred)
Benefits of using digoxin for AF
Causes less bradycardia than β-blockers, and do not reduce cardiac contractility as much as Ca channel blockers.
Magnesium sulfate - Indications
Drug-induced torsades de pointes.
Digitalis-induced ventricular arrhythmias.
Supraventricular arrhythmias associated with Mg deficiency.
What diseases may be caused by magnesium deficiency?
Arrhythmias, congestive heart failure, GI and renal disorders.
Ivabradine - MOA
Heart rate-lowering drug that block the funny current (If, mixed Na, K inward current) in the SA node.
Ivabradine - indications
Angina, heart failure, inappropriate sinus tachycardia.
Ivabradine - interactions
Metabolized by CYP3A4. With inhibitors of this enzymes ivabradine may cause excessive bradycardia.
Ivabradine - contraindications
Concurrent use of strong CYP3A4 inhibitors
Ivabradine - adverse effects
Excessive bradycardia.
