There are several reports indicating that the peformance of a pharmacuetical dosage form is influenced by the changes in suppliers of the same excipient due to the variations in physicochemical properties and quality of excipient. There is increased demand for excipients with pre-determined specifications to control the physical properties of excipients like size, shape, tecture, density and moisture content. Spray dried excipients improves the flow property and freeze dried excipients enhances the dissolution rate. The moisture content of excipient influences the hardness, chemical stability and dissolution rate. Amount of emitted dose and the fine particle fraction from the dry powder inhalers is influenced by the particle size of the carrier. Physical properties of the excipients influence the direct compressible properties of the diluent. These physical properties can be manipulated by changing the conditions during the manufacture of these excipients. Another option to improve these physical properties of these excipients is to alter them chemically by subjecting them to cross linking or carrying out reactions like substitiution, condensation, hydrolysis etc. Ex: Croscarmellose sodium which is a cross linked form of Sodium CMC is used as superdisintegrant, Cross linked gelatin is used to formulate the microcapsules. Modified excipients improves the flow properties, compressibility, dissolution characterstics. Recently, they are also widely employed in formulating the oro-dispersible tablets.
1) Raymond C Rowe Hand Book of Pharmaceutical excipients Pharmaceutical
press 6th edition
2) Sunita A Chaudary et.al. Excipeints updates for orally disintegrating dosage
forms Int.J.Res.Pharm.Sci. Vol-I, Issue-2, 103-107, 2010.