The objective of this chapter is to introduce the antiarrhythmics. Antiarrhythmics are drugs that are used to treat abnormal heart rhythms resulting from irregular electrical activity of the heart. This chapter covers the pentoxifylline, amiodarone, adenosine, isoprenaline, aspirin, tenecteplase, and lidocaine along with their indication, dose, contraindication, precaution, adverse effect, and drug interaction. Coronary vasodilator, paroxysmal supraventricular tachycardia, cardiac imaging for coronary artery disease, and angina pectoris are the indications of adenosine.