An old man enters a hospital with myocardial infarction and severe ventricular arrithmia. The antiarrhythmic drug chosen has a narrow therapeutic window. The minimum toxic plasma concentration is 1.5 times a minimum therapeutic plasma concentration. Day half life is 6 hours. It is essential to maintaining the plasma concentration about the minimum therapeutic level to prevent possible lethal arrhythmia. Of the following the most appropriate dosing regimen would be