This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Pharmacology
Dofetilide belong to? 
Select and explain. 
A. Class I antiarrythmic, B. Class II antiarrythmic, C. Class III antiarrythmic, D. Class IV antiarrythmic
C: Class III antiarrythmic
Answer: C: Class III antiarrythmic 
Explanation: Ibutilide, dofetilide, sotalol, amiodarone are class 3 agents they are potassium channel blockers- they r broad spectrum antiarrhythmic agents they increase QT interval