Class iii antiarrhythmics

A 81-year-old man on chronic warfarin therapy for atrial fibrillation is planning on starting amiodarone for rhythm control. How should his dose of warfarin be adjusted after starting amiodarone?

1: He can stop taking warfarin immediately
2: He should continue his dose of warfarin unchanged
3: His dose of warfarin will need to be increased
4: His dose of warfarin will need to be reduced