Procainamide is used for the treatment of ventriculartachyarrhythmia. It is administered intravenously, orally andintramuscularly, and its therapeutic range is 4-8 ug/mL. When a 450mg dose is administered intravenously to a normal healthysubject:
◦ The elimination half life = 3 hours
◦ The apparent volume of distribution = 2 L/kg
When a 500 mg procainamide tablet is administered orally to ahealthy subject (75 kg), the following parameters were determinedfrom the plasma concentration vs. time curve.
◦ The absorption rate constant = 2.8 hr-1
◦ The fraction of dose absorbed = 85.54%
◦ The intercept of the plasma concentration time curve = 3.33ug/mL
1) If two 500 mg procainamide tablets are given to a 70kgpatient with normal absorption and clearance functions every 6hours, calculate
-Peak and trough concentration at the steady state
-Average plasma concentration at the steady state
2) In a 70 kg patient with renal impairment, the eliminationhalf life of procainamide is reported to be 14 hours, but theabsorption rate is not affected. What would be the maintenance andloading doses to keep the plasma level above the minimum effectivelevel (4 ug/mL)? Procainamide tablets are available in 250 and 500mg tablets.
