Nelerabine is an antineoplastic drug used to treat various types of cancer. However, the drug may contain impurities that can affect its safety and efficacy. Nelerabine impurities can result from the manufacturing process or degradation of the drug during storage. These impurities can potentially cause adverse effects and must be monitored and controlled to ensure patient safety. Analytical methods are used to detect and quantify these impurities, and their levels must be kept within acceptable limits.