Effect of storage conditions on the stability of ascorbic acid in some formulations

Objective: The stability of ascorbic acid is affected by temperature, pH, sunlight and the presence of metals like copper and iron. The study seeks to investigate the effect of storage conditions on the stability of ascorbic acid in tablets (buccal tablets) and syrups sampled from the Ghanaian market. Methods : Ascorbic acid tablets were sampled and stored separately at room temperature and under refrigeration (in a fridge) and assayed periodically for 35 d. Ascorbic acid syrups were also sampled and stored at room temperature, in a bowl of water and under refrigeration and also assayed periodically for 35 d. The mode of assay was iodimetry. Results : For both formulations, storage under refrigeration saw the least breakdown and at room temperature, the breakdown of ascorbic acid was greatest. The syrups stored in a bowl of water were more stable than those stored at room temperature. The % breakdown of ascorbic acid in the syrups and tablets stored at room temperature were statistically significant in comparison to that under refrigeration as determined by a T-test. The % breakdown of ascorbic acid in the syrups stored in a bowl of water was not statistically significant in comparison to that under refrigeration. Conclusion : Ascorbic acid formulations should be stored under refrigeration or at low temperatures if possible. In the absence of refrigeration, patients should be advised to store syrups of ascorbic acid in a bowl of water and the tablets at cool places in homes.