Question

10) Which of the following drugs act also on
phase III
A)
Classia
B)
Class I b
C)
Classic
D
None of the these
​

Answer 1

Answer:

C. classic is the right option

Answer 2

• In addition to blocking sodium channels, class Ia medicines also block potassium channels.
• As a result, they influence both phase 0 and phase III.
• They may lengthen the QT interval in the ECG and trigger Torsade De Pointes due to their phase III effect.

Class I:

Class Ia: causes fast sodium channels to be moderately blocked.

• Procainamide, disopyramide, and quinidine are examples of drugs.
• Because of their prolonged QTc interval, these sodium channel blockers have the highest proarrhythmic potential of all those studied; their usage is therefore restricted.

Class Ib: moderate sodium channel obstruction is caused by this.

• Mexiletine and lidocaine are medications.
• The QTc interval is shortened by these medications, which are only used for VA, particularly post-myocardial infarction VA.
• They are not helpful for atrial arrhythmias.
• Mexiletine reduces recurring and ICD arrhythmias and shortens the QTc interval in long QT syndrome.

Class Ic: causes a significant amount of sodium blockage without affecting the QT interval.

• Drugs can be propafenone or flecainide.
• These medications are appropriate for continuous therapy in individuals with symptomatic supraventricular tachycardia (SVT) who do not have structural heart disease or ischemic heart disease and are not candidates for catheter ablation or do not want to.

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