Procainamide is an antiarrhythmic drug that has Vd of 2 L/kg and k of 0.2 hr-1. After iv administration 40% of procainamide dose is metabolized to NAPA and the rest of the dose is excreted unchanged in urine. NAPAs Vd is 1.5 L/kg and k is 0.1 hr-1. After iv administration of NAPA 80% of the dose is excreted unchanged in urine. What is the metabolic clearance of procainamide ?