Recent Advances in Drug-in-Adhesive Transdermal Patches: Innovations in Materials, Formulations, and Delivery Mechanisms.

INTRODUCTION/OBJECTIVE: This review examines recent developments in transdermal drug delivery systems, with emphasis on drug-in-adhesive patches. It aims to summarize advances in patch design, formulation strategies, and methods used to improve drug permeation and delivery performance. METHODS: This narrative review was conducted through a literature search of PubMed, Scopus, and Web of Science. Search terms included combinations of 'drug-in-adhesive patch', 'pressure-sensitive adhesive transdermal', 'hydrogel adhesive', 'penetration enhancer', 'ionic liquid transdermal', and 'active pharmaceutical ingredient crystallization adhesive matrix'. Studies were selected based on relevance to drug in adhesive patch formulation, adhesive material performance, and permeation enhancement strategies, with priority given to original research articles published in peer-reviewed journals. A total of 129 references are cited in this review. RESULTS: New adhesive materials, including acrylic-based and hydrogel-based systems, have been developed to improve skin adhesion and compatibility with diverse drug molecules. Significant progress has been made in enhancing drug permeation through chemical penetration enhancers and approaches involving ionic liquids. Key formulation challenges, such as drug crystallization within the adhesive matrix, stability, and control of release kinetics, remain active areas of investigation. Research increasingly emphasizes understanding the molecular state of drug substances within the patch to optimize delivery efficiency. DISCUSSION: The findings demonstrate meaningful advancement in materials and formulation methods that support more effective and patient-friendly transdermal patches. These developments align with broader efforts to improve therapeutic outcomes, reduce dosing frequency, and enhance patient compliance. Persistent limitations include the need for standardized testing approaches and a deeper understanding of long-term stability and skin interactions. Future work should address these gaps while exploring novel materials and permeation strategies. CONCLUSION: Advances in drug-in-adhesive transdermal systems show strong potential for improving drug delivery. Continued innovation in adhesive design, permeation enhancement, and formulation science is essential for developing next-generation transdermal therapies.