Class 3 (Anti-Arrythmics) Flashcards
What are Class 3 drugs?
Voltage Dependant Potassium channel blocking drugs.
What do Class 3 do?
It will take forever for basically any cell to repolarize.
What do Class 3 do to cardiac myocytes?
Basically makes APD longer and as a result increases the ERP. It does so by prolonging the repolarization phase.
Name the prototypical Class 3 drug and what it does?
Amiodarone, this drug mimics Class 1 (sodium blocker) class 2 (Beta blocker) class 3 (K blocker) and class 4 (Ca channel blocker). There is also Sotalol.
What does Amiodarone do? When to use?
Increase APD and ERP, can be used for any arrythmias and in all cardiac tissues.
What are the problems with Amiodarone?
Absurd half life of 80 days because of high tissue protein binding (it will iodinate proteins and make a covalent bond with them, stay stuck), almost 3 months! 4-5x needed to reach steady state so effects kick in very slowly, toxicities become tough to manage.
What adverse effect does Amiodarone have on lung tissue?
Causes pulmonary fibrosis, and thus decreases TLC and has FEV/FVC will be normal or elevated because this is a restrictive lung disease.
What are the side effects associated with Amiodarone?
Pulmonary fibrosis, “Smurf Skin” (blue pigmentation of skin), phototox, corneal deposits, hepatic necrosis, thyroid dysfunction.
What’s special about Sotalol?
It has both K+ and ß1 blocking effects.
What does Sotalol do?
Decrease HR, decrease AV conduction and slows phase 3 of cardiac myocytes (prolongs repol).
When to use Sotalol?
During life threatning ventricular arrythmias.
