The skin, as the largest organ of the human body, plays a vital role in protection, Thermoregulation, and sensory perception. It also serves as a complex and selective barrier to external agents, making it both a challenge and an opportunity for pharmaceutical interventions. This review provides a comprehensive overview of the skin’s anatomy and physiology, highlighting the structural features of its three primary layers: the epidermis, dermis, and hypodermis. Special emphasis is placed on the stratum corneum, the outermost layer, which poses the main barrier to drug penetration. Understanding the skin’s functional dynamics is essential for optimizing topical and transdermal drug delivery. The article explores conventional and advanced drug delivery systems utilized in dermatological and cosmetic formulations, including creams, ointments, gels, patches, liposomes, and nanoparticles. Recent advancements in nanotechnology and biocompatible carriers have enhanced drug solubility, stability, and targeted delivery, thereby minimizing systemic side effects while improving therapeutic outcomes. Additionally, techniques such as microneedles, iontophoresis, and sonophoresis are discussed for their potential in overcoming the skin barrier and delivering drugs effectively to deeper layers. This review also examines key factors that influence drug permeation, including molecular weight, lipophilicity, formulation pH, and skin condition. Regulatory considerations, formulation challenges, and patient compliance issues are addressed to provide a holistic view of pharmaceutical skin care. By integrating skin biology with novel drug delivery approaches, this article aims to inform the development of more effective, patient-friendly dermatological therapies and cosmeceutical products. Future directions emphasize personalized formulations, innovative delivery systems, and sustainable ingredients to meet the evolving needs of patients and the market. Keywords: Skin, layers, Formulations, Drug delivery system
Prajapati et al. (2025) studied this question.