 Other common side effects of NAPA are gastrointestinal disturbances, insomnia, dizziness, lightheadedness, blurred vision, numbness and tingling sensation.There has been a large resemblance reported between the concentration range associated with arrhythmic suppression of acecainide and the range of concentrations where intolerable side effects begin to develop.No severe cardiac toxicity has been notified with oral intake despite plasma concentrations as high as 40 micrograms/ml.