2-Hydroxypropyl β-Cyclodextrin: A New Tool for the Improvement of Chemical Stability of Tiagabine HCl

The aim of this paper was to describe the use of a 2-hydroxypropyl beta-cyclodextrin (2-HP beta CD) as a tool to improve the chemical stability of tiagabine hydrochloride (TGB). HPLC method was used to quantify TGB. The correlation coefficient of the linearity (r(2)) of HPLC method was more than 0.999 whilst the limit of detection and the limit of quantification of TGB were 0.6494 mu g ml(-1) and 1.765 mu g ml(-1) respectively. The effect of 2-HP beta CD on the chemical stability of TGB was compared with tocopherol and ascorbic acid, the most recognized antioxidants used to enhance the stability of TGB. The stability was expressed by (% w/w) of the total related substances (TRS) of TGB. When TGB was exposed for 24 h to 50 degrees C, the TRS were 3.264% (SD +/- 0.077) and 3.125% (SD +/- 0.053) in the presence of tocopherol and ascorbic acid, respectively. The TRS of TGB complexed with 2-HP beta CD was 2.142% (SD +/- 0.045). This study demonstrates that 2- HP beta CD exhibits an obvious enhancement of TGB chemical stability with a different mechanism compared with the usual antioxidants.