FUNCTIONALITY TESTING OF EXCIPIENTS: A REVIEW

The quality of medicines depends not only on the active principles and production processes, but also the performance of the excipients, hence we say’ Excipients are Cindrellas of Formulation’. The traditional concept of the excipient as any component other than the active substance has undergone a substantial evolution from an ‘inert’ and cheap vehicle to an essential constituent of the formulation. The rapid evolution of scientific, regulatory and economic factors, the introduction of delivery systems and the advance in biopharmaceutics have led to a new interest in the role and functionality of the excipients. There are number of raw materials available from a multitude of sources used in pharmaceutical industry where their chemical structures vary from small polymer to long chain polymer. Excipients are now chosen to perform a variety of functions which guarantee the stability and bioavailability of the drug substance and its manufacturability on a large production scale. Beyond the dosage form necessities, excipients particularly in the case of solid dosage forms are used. As a consequence, their characterisation must go beyond the simple tests for identity, purity and strength as prescribed in general by the Pharmacopoeia monographs. Full physical characterisation of solid materials is now made possible with the help of high resolution analytical techniques on the molecular, particulate and bulk levels, this approach now has become necessary to guarantee the behaviour of the excipient during the formulation and production phases of all solid and liquid dosage forms. Excipient harmonisation, standardised functionality tests, preformulation data bases will contribute to change the conventional trial-and-error formulation approach into a far more scientific and technological development. Hence study of excipient has now gained importance which would lead to develop new formulation