Why must contaminants be removed from synthetic drugs?

In the context of chemical synthesis, synthetic products are typically contaminated with reagents, by-products, and unreacted starting materials. These contaminants must be removed to ensure the final substance is pure.12

Achieving high purity is a fundamental ethical and practical requirement in medicine and manufacturing, as the presence of impurities can compromise the safety, efficacy, and intended function of the final product. In multistep synthesis, it is standard practice to purify the product at each stage to prevent the accumulation of impurities that could interfere with subsequent reactions. Techniques for achieving this are central to the field of separation and purification.312