Chronic diseases represent a significant global health challenge and often necessitate prolonged or lifelong pharmacotherapy to achieve optimal therapeutic outcomes and prevent disease progression. Conventional drug delivery routes, particularly oral and parenteral administration, are frequently associated with several drawbacks, including poor patient adherence, gastrointestinal side effects, inconsistent bioavailability, and extensive hepatic first-pass metabolism. These limitations are further intensified during long-term treatment, where repeated dosing and fluctuating plasma drug concentrations may negatively affect therapeutic efficacy. Consequently, there is an increasing need for alternative drug delivery strategies that can offer sustained, safe, and patient-friendly treatment options. Transdermal Drug Delivery Systems (TDDS) have gained considerable attention as an effective alternative for the management of chronic diseases by facilitating controlled drug transport across the skin directly into systemic circulation. The transdermal route provides multiple advantages, such as bypassing first-pass metabolism, maintaining consistent plasma drug levels, minimizing dosing frequency, and enhancing patient compliance. These benefits make TDDS particularly advantageous for chronic conditions including cardiovascular disorders, chronic pain, neurological diseases, hormonal imbalances, and smoking cessation, where continuous and controlled drug delivery is essential. However, the skin functions as a highly efficient protective barrier, restricting the permeation of most therapeutic agents.