Stability of procainamide hydrochloride syrups compounded from capsules

The stability of procainamide hydrochloride in two oral syrups, one prepared with sucrose and the other with maltitol, was studied. A syrup containing powder from 500-mg procainamide hydrochloride capsules, simple sucrose syrup, and other additives was prepared; the theoretical initial concentration of procainamide hydrochloride was 50 mg/mL. Three samples each were stored at 40, 50, 60, and 70 degrees C. Drug concentration was measured with high-performance liquid chromatography at times ranging from 2 to 107 days. In a second study, a syrup containing powder from 500-mg procainamide hydrochloride capsules, a maltitol-based syrup vehicle, and other additives was prepared; the theoretical initial drug concentration was 50 mg/mL. Three samples each were stored at 40, 50, 60, and 70 degrees C. Drug concentration was measured at times ranging from 7 to 187 days. For the sucrose-based syrup, there was apparent first-order degradation of procainamide hydrochloride at all temperatures. An Arrhenius plot was used to calculate a shelf life of the syrup of 456 days at 25 degrees C. Most samples turned brown over time, and pH values were constant. For the maltitol-based syrup, drug degradation appeared to be biphasic; an initial period during which concentrations remained at nearly 100% was followed by apparent first-order degradation. Arrhenius plotting gave a shelf life of 97 days at 25 degrees C. Most samples turned brown over time, and pHs remained constant. Arrhenius plots indicated that in a maltitol-based oral syrup, procainamide hydrochloride was more stable than in a sucrose-based syrup when the storage temperature was above 37 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)