Earlier (in last year's report) it was reported that the formulations containing 250 mg of Vit. E acetate (50% SD) and 100 mg of Vit. C required for this project were found to darken during storage and that on subjective analysis, the most stable formulation was the one containing pure crystalline Vit. C rather than those containing 90%, 97.5% or 98.4% commercial coated Vit. C. Subsequently, the samples of various formulations have been analyzed by using an equipment called Colorguard System 2000 (Pacific Scientific) and results confirm to initial findings. It was further determined that the color deterioration was due to Vit. C and as such Vit. E Acetate did not play any role. However, moisture picked up by the used solid dispersion of Vit. E Acetate (50% SD) because of its hygroscopic nature was instrumental in inducing the darkening process. Also, moisture picked up during weighing, mixing and handling was more crucial than after the compression of tablet. This was evident by the fact that inclusion of silico gel bags in the storage vials did not deccelerate the discoloration process whereas avoidance of moisture during handling prior to compression improved the color stability. A revised formulation using pure crystalline Vit. C as well and improved processing conditions has been recommended for this product.
