by Elena BOLDYREVA, Dr. Sc. (Chem.), Head of the Chair of Chemistry of Solids at the Novosibirsk State University and Chief Researcher of the Group of Reactivity of Solids at the Institute of Chemistry of Solids and Mechanical Chemistry, RAS Siberian Branch
Development of new efficient drugs is a long and labor-consuming process. It involves long-term efforts both of scientists and engineers including specialists in physical pharmacy which is based largely on the achievements in solid state chemistry, physical chemistry and crystallography.
Compounds or drugs?"--this is a question on the cover of the October 2011 issue of Chemistry and Engineering News published by the American Chemical Society. Pharmaceutical compounds, whether synthesized artificially or extracted from a natural raw material, are powders or liquids, which are in most cases not yet suitable to be used as drugs. To become a drug, a pharmaceutical compound must be a component of a solution for injections, a tablet, a syrup, an ointment, a spray, a plaster, or even of a chewing gum or a candy. Pharmaceutical formulations contain also a considerable share of auxiliary inert substances, fillers or, as they are also called--excipients. They are added to simplify the process of preparation of a drug, to increase its shelf-life, ease of use, bioavailability or bioactivity. For example, the following properties can be improved: compressability and mechanical strength of tablets, their hygroscopicity (susceptibility to humidity), rate of dissolution, target delivery to appropriate organs or even cells (for example, cancer cells), taste, smell and color. Different pharmaceutical formulations can contain substances of the same chemical composition but with a different crystal structure (polymorphs), or amorphous, can differ in size and shape of the particles, they can be classified chemically as salts, multi-component crystals (cocrystals, solvates, molecular complexes), mechanical mixtures or ... Read more