N.A. Polyakov - Ph.D. (Biol.), Leading Research Scientist, All-Russian Science Research Institute of Medicinal and Aromatic Plants (VILAR) , Moscow, Russia. Е-mail: polakov@yandex.ru
V.A. Dubinskaya - Ph.D., All-Russian Institute of Medicinal and Aromatic Plants, Moscow, Russia. E-mail: va@diamsoft.ru
V.F. Okhotniva - Ph.D. (Pharm.), Manager of Pharmaceutical Technology Section, All-Russian Institute of Medicinal and Aromatic Plants, Moscow, Russia. E-mail: vilarnii@mail.ru
M.M. Astrahanova - Dr. Sc. (Pharm.), Professor, Research Institute of Pharmacy, First Moscow State Medical University named by I.M. Sechenov. E-mail:Nalya-Niif@mail.ru
A.A. Levin - Ph.D. (Chem.), Manager of Chemistry Analytical Section, State Research Centre «NIOPIK». E-mail: to@niopik.ru

Information about state of water, water absorption and thermodynamic characteristics of excipients, as well as effecting on these parameters of experimental ageing, plays а key role in technology, standardization, and determination of terms and conditions of drugs storage. Results of definition water content of excipients and drugs in contemporary foreign and domestic literature have various values, at the same time water method often is not specified. Therefore, the purpose of the given work was comparative studying of methods definition of water content and physical and chemical properties of excipients and drugs. For investigation following methods have been used: a drying method at 105 0C, recommended by Russian XI pharmacopoeia, Fisher's method, isotermic vapor sorbtion method at relative humidity range from 3 to 98 %, differential scaning calorimetry, IR-spectroscopy and method of accelerated ageing at temperature 50 ºC during time equivalent to 1 and 2 years of storage. By using method of differential scaning calorimetry not only structure of substances, but also various forms of water different binding capacities, and change of excipients physical condition were established that do possible use this method for the control quality of excipients and drugs in technological stages at various temperature modes. Investigated physical and chemical properties of excipients and drugs (crystalline hydrate and unhydrate form, temperature range of water evaporation), influence on choice of method definition of amount of water. In the course of experimental ageing of excipients formed intermolecular cross-linking between groups of molecules reducing solubility.