Cleaning validation is a crucial process in pharmaceutical manufacturing to ensure equipment is free from harmful residues from previous products, including active pharmaceutical ingredients (APIs), excipients, and cleaning agents. This process ensures consistent removal of residues, preventing cross-contamination and maintaining product quality and safety. Key aspects of cleaning validation include adhering to regulatory guidelines, using analytical techniques like HPLC and TOC analysis, selecting a "worst-case" product for validation, using sampling techniques like swab and rinse sampling, defining acceptable residue levels based on toxicity and daily dose, and establishing a detailed validation protocol. The importance of cleaning validation lies in preventing cross-contamination, ensuring product quality and safety, complying with regulations, protecting brand reputation, and reducing the risk of product recalls and other costly consequences associated with contamination. It is mandated by regulatory bodies like the FDA, EMA, and WHO to adhere to Good Manufacturing Practices (GMP). Terbinafine, a synthetic allylamine antifungal drug, is highly lipophilic and tends to accumulate in skin, nails, and fatty tissues. It inhibits ergosterol synthesis by inhibiting the fungal squalene monooxygenase enzyme. Terbinafine hydrochloride was granted FDA approval on 30 December 1992. Validating a cleaning procedure for residual drug determination in manufacturing aims to demonstrate that the process consistently removes drug residues from equipment to levels below predetermined acceptance criteria, preventing cross-contamination and ensuring product purity and safety. This involves establishing residue acceptance criteria, selecting appropriate analytical methods, developing a robust cleaning process, conducting validation studies, demonstrating reproducibility and repeatability, identifying potential risks, ensuring patient safety, meeting regulatory compliance, and maintaining product quality by preventing cross-ontamination between different drug products produced on the same equipment.