چکیده (انگلیسی):

The objectives of this study were to determine the cause of the crystallization in a large volume creatine supplement solution made from effervescent powders containing di-creatine citrate, and to characterize these crystals using thermal analyses and x-ray diffractome-try. Creatine effervescent powders were dissolved in deionized water (pH 6.2) and stored both at room tem-perature (RT) (25°C) and refrigerated condition (4°C) over a period of 45 days. Creatine concentration was determined using high-performance liquid chromatog-raphy (HPLC). Intrinsic dissolution and saturated solu-bility of creatine, creatine monohydrate, and di-creatine citrate in water were determined and compared. Crystal growth was detected only in the refrigerated samples on the seventh day of storage. Differential Scanning Calorimetry (DSC) and x-ray diffraction (XRD) studies revealed that the crystals formed were of creatine monohydrate. Ninety percent creatine degradation was observed within 45 days for RT samples. However, at refrigerated condition this degradation was 80% within the same time period. The pH of the RT samples also increased from 3.6 to 4.5 during storage. No such in-crease was observed in the case of refrigerated sam-ples. The intrinsic dissolution rate constants of the compounds decreased in the following order: di-creatine citrate > creatine > creatine monohydrate. In conclusion, di-creatine citrate used in effervescent for-mulation dissociates to creatine in aqueous solution and eventually crystallizes out as creatine monohydrate. Significant decrease in solubility and effect of pH con-tribute to this crystallization process.