3.5. Accelerated stability study
The suggested protocol was applied for assessment of a commercially available GT formulation. Tablets were exposed to stress conditions of 40 ± 2 °C and 75 ± 5% relative humidity for a total period of six months according to ICH guidelines (ICH, 2003). Samples were withdrawn after one, three and six months and the described protocol was applied. Results were compared to those obtained from control tablets of the same batch that were stored protected from light at ambient temperature and humidity. The recovery % of GA as well as caffeine content was calculated. Effect of incubation of GT tablets under the studied stress conditions was expressed as the % loss of EGCG. This was calculated relative to the values obtained from the control tablets (Table 3). Results showed that % loss in EGCG was 24.0%, 28.0% and 52.0% after one, three and six months, respectively. The percentage loss of EGCG significantly exceeded the recommended values of ICH guidelines (ICH, 2003).