RESUMO
AIM: To investigate the effectiveness of dosing technology and excipient application on solid drug's moisture-proof property and to provide a method improving the solid drug's moisture-proof property. METHODS: Based on the analysis of the moisture absorbing process and the absorbing mechanics,a new concept "active moisture absorbance site"(AMAS) was defined and mathematic model was constituted.Two constants as: initial AMAS concentration C_0,moisture resistance coemcient K,were proposed to indicate the drugs moisture-proof ability. The CI WU JIA extracts and SHUANG HUANG LIAN extracts were used to conduct experiments, which were designed to investigate the improvement of the drug's moisture resistance ability when varying the AMAS's concentration and/or its space distribution. RESULTS: Reducing the amount of moisture absorbance excipients in each dosage of solid drug can lower the drug's moisture absorbance ability,and applying a thin film coating material outside the drug can also slow the drug's moisture absorbance rate. CONCLUSION: The proposed mathematic model is useful for finding a way to improve the drug's moisture resistance;experimental data shows that the drug's moisture-proof property would be improved by reducing the amount of moisture absorbance excipient in each dosage and improving the moisture distribution resistance through a certain dosing technology,such as film coating technology.