Class 1
What channel is predominately blocked in class 1 antiarrhythmics and what phase of the action potential is associated with it?
Na+ channels, phase 0
What channel does a beta blocker block?
Phase 4/funny current channels (Na+)
What channel is blocked in class 3 antiarrhythmics?
K+ channel (phase 3)
What channel do these drugs block?
Calcium channels (phase 0 in pacemaker AP)
What is the MOA of digoxin?
Name 2 class 1A drugs.
1. S/E: cinchonism
2. causes drug induced lupus
Quinidine, procainamide
What cells do beta blockers predominately target?
SA node, AV node (pacemaker cells)
What is the major feared side effect of class 3 drugs?
Increased QT interval --> torasdes de pointes
Name 2 class 4 calcium channel blockers
verapamil, diltiazem
What drug is this?
Very short acting, effects blunted by theophylline, can cause dyspnea and chest pain (impeding sense of doom), is a vasodilator
Adenosine
In tachycardia and ischemic conditions due to more depolarized myocytes and increased binding of the drug, which class 1 drugs should be used?
Type 1B - lidocaine, mexiletine
Which class 2 drug should be used with caution when treating diabetic patients?
Propanolol
Which drug causes pulmonary fibrosis and blue man syndrome as a side effect?
Amiodarone
Which phase of the pacemaker action potential do these drugs prolong (in addition to blocking calcium channels)
phase 4 spontaneous depolarization
What is the treatment for torasdes de pointes?
Magnesium
What is the phenomenon called when drugs tend to be more active at ion channels that are depolarizing more frequently? (all class 1 drugs have this)
Use-dependent
Which beta blocker specifically treats HTN and chronic CHF?
Carvedilol
Which drug can be used for chemical cardioversion?
Ibutilide
Incorrect dosage of class 4 drugs and beta blockers could lead to this adverse side effect.
AV block (type 1 or type 2 mobitz type 1)
Magnesium
Which drug is contraindicated post-MI?
Which beta blocker can treat wide angle glaucoma?
Timolol, metoprolol
Explain the concept of reverse-use dependence.
They are more active in prolonging the action potential at slower heart rates, rather than faster heart rates. (drug binds best when potassium channel is at rest)
What change will you see on EKG when a patient is on a class 4 drug?
Increased PR interval
Milrinone is a PDE inhibitor which increases cAMP. When cAMP acculumates, it inhibits this enzyme which then causes vasodilation. What enzyme?
MLCK - myosin light chain kinase