Formulation-related impurities in drug substances

Various impurities can appear in the drug product when excipients are used in a drug substance formulation. Moreover, there are different conditions in the process of formulating a pharmaceutical substance, which can cause its degradation or other undesirable reactions. Due to hydrolysis or solvolysis, suspensions and solutions are subject to degradation.

The same reactions can also occur in solid dosage form in the case of capsules and tablets, as a solvent or water is used in the granulation process. The water used in the formulation can not only contribute its impurities, but can also provide an ideal condition for the metal catalyst and hydrolysis. Comparative reactions can be visualized in other usable solvents, if care is not taken, oxidation is quite possible for oxidizing materials. Similarly, the photosensitive material can support photochemical reactions. The mainly reactive impurities are small molecules. In addition to chemical stability, impurities in pharmaceuticals can lead to performance issues in the form of toxicity or dosage.

Periodically, it is important to quantitatively determine the level of significant impurities in pharmaceuticals and to find the origin of these impurities at their source using the analytical method.