Pharm: Anti-Arrythmics

Question 1

Ca2+ channel blockers slow what phase of depolarization?

Answer 1

phase 0, the threshold-reached upstroke, blocked by Class 4 drugs like verapimil and diltiazem

Question 2

what determines the refractory period of fast response myocytes?

Answer 2

Na+ channels, blocked by Class 1 drugs like procainimide, lidocaine

Question 3

nifedipine is what class of drug?

Answer 3

dihdropyridine Ca2+ blocker, reduces refractory period of fast response cells

Question 4

SERCA?

Answer 4

sarcoplasmic reticulum calcium ATPase pump

Question 5

what does class 1a do?

Answer 5

fast-acting cell binds to open Na+ ion channel and increases repolarization time; procainimide

Question 6

class 1b?

Answer 6

binds to both open and closed Na+ in fast acting myocytes, has small elongation of refractory phase; lidocaine

Question 7

class 1c?

Answer 7

flecainide, no effect on repolarization (aka QT) interval

Question 8

class 2?

Answer 8

B blockers like metroprolol and propranolol, atenolol (atenolol and metroprolol are B1 selective)

Question 9

class 3?

Answer 9

K+ channel blockers. they prolong the QT interval by blocking K+ flow during plateau phase and preventing cells from repolarizing; eg amiodarone, sotalol, ibutilide

Question 10

class 4?

Answer 10

Ca2+ channel blockers, act primarily on pacemaker cells, eg verapimil and diltiazem

Question 11

choice for a-fib?

Answer 11

shock or procainimide

Question 12

choice for v-tach?

Answer 12

amiodarone

Question 13

choice for ventricular premature beats?

Answer 13

amiodarone (it’s class 3, lengthens the QT interval by blocking K+ induced repolarization)

Question 14

choice for PSVT?

Answer 14

adenosine (in-patient) or verapamil