Pharmaceutical products are not composed solely of active pharmaceutical ingredients (APIs). They also include a variety of other substances that are essential for ensuring product stability, safety, manufacturability, and patient compliance. These additional substances are known as excipients. While often referred to as "inactive ingredients," excipients play critical roles in formulation science. They are deliberately included to enhance drug solubility, improve bioavailability, extend shelf life, and optimize drug delivery, among other functions. In this context, the International Pharmaceutical Excipients Council (IPEC) defined excipients as "substances other than the API that have been appropriately evaluated for safety and are intentionally included in a drug delivery system." Their functions can be technological (facilitating processing), biological (improving absorption or stability), or patient-centered (enhancing taste, appearance, or ease of use). In modern pharmaceutical development, excipients are as indispensable as APIs themselves, enabling the creation of medicines that are both effective and patient-friendly.