What Are Residual Solvents?

Residual solvents in pharmaceuticals refer to organic volatile compounds that are used in the production of drug substances, excipients, and preparations but have not been completely removed during the process. In the drug substance synthesis process, selecting the appropriate solvent can increase the yield or determine the properties of the drug, such as crystal form, purity, and dissolution rate. Therefore, organic solvents are essential and very critical substances in drug synthesis reactions. When the level of residual solvents in medicines is higher than the safe value, it will be harmful to the human body or the environment, so the control of residual solvents has attracted more and more attention.