Steady-state plasma and saliva concentrations of procainamide and N-acetyl-procainamide after a sustained release preparation
Pirovino, M.; Karlaganis, G.; Galeazzi, R.L.
Schweizerische Medizinische Wochenschrift 110(39): 1415-1419
1980
ISSN/ISBN: 0036-7672 PMID: 6169144 Document Number: 167170
With ordinary procainamide tablets a dosing interval of 3-4 hours must be chosen to achieve therapeutically useful plasma concentrations during the entire interval. The concentrations of procainamide and its N-acetylated metabolite, NAPA, have been studied in the plasma of 10 normal volunteers and 11 patients who were given a new sustained release preparation at 8 hour intervals. Blood samples were taken between two doses on the fourth day of treatment. Procainamide showed levels within the accepted therapeutic range during the entire dosing interval. A dose of 4.5 g per day per 70 kg body-weight is necessary in order to achieve adequate levels. NAPA concentrations did not fluctuate during the dosing interval and mean steady-state concentrations were influenced predominantly by the degree of renal function. Saliva to plasma concentration ratio, measured in four patients, showed huge inter- and intraindividual variability. Therefore, saliva concentrations measurements of procainamide and NAPA are of little clinical use.