Abstract:

This study aimed to investigate the effects of different process parameters on the physical properties, in vitro dissolution rate, and short and long-term stability of diclofenac potassium (DFP) granules and capsules. DFP granules exhibited low total amounts of impurities when prepared through the wet granulation method using a granulating solvent with a low water/ethanol ratio. The impurities of the wet DFP mass dried at 70 °C were higher than those dried at 50 °C or 60 °C. DFP granules were stable under strong light exposure during preparation. DFP granules prepared using a granulating solvent with a 1:4 water/ethanol ratio had a relatively smaller particle size and higher angle of repose than those prepared using granulating solvents with other water/ethanol ratios. The dissolution rate of DFP capsules prepared using four different water/ethanol ratios was less than 2% after 10 min of dissolution and increased to 95% within 30 min of dissolution. The total amount of drug impurities of DFP capsules prepared using a granulating solvent with 1:4 water/ethanol ratio was considerably lower than those of DFP capsules prepared using a granulating solvent with a 1:0 water/ethanol solvent ratio. Regardless of the water/ethanol ratio, the capsules showed poor stability when exposed to high temperature (60 °C) and strong light (4500±500 Lux) for 10 days, but were relatively stable at high humidity (92.5% RH). The results of the long-term stability (25±2 °C and 60%±10% relative humidity) study showed that DFP granules were more stable than DFP capsules, and were stable for 12 months. The type of encapsulating material did not affect the 2-month stability of DFP. DFP granules are sensitive to granulating solvent and drying temperature and DFP capsules should be stored away from high temperature and strong light. 

Key words: Diclofenac potassium, Wet granulation, Physical properties, Stress test, Long-term stability