Effects of excipients on the stability of medicinal products
Excipients play important roles in delivery, manufacture and performance of medications. Dosage form design programmes involve choosing the most appropriate excipients, their optimum inclusion levels and the best mode of incorporation in the product. However, interactions between a drug and the excipients with which it is co-formulated in a medication can compromise the quality, efficacy or even safety of the product. Such effects may be due to direct drug: excipient interactions or reactions between drug and residues or impurities in the excipient. These may lead to the formation of new molecular constructs (degradation products) or a changed physical form of the drug. Drug substance characterization and dosage form design programs need to be explore such interaction possibilities to help choose excipients that are compatible with the drug. such investigations will reduce the risk of problems arising later in the program as instability often takes some time to be manifest.