Spray drying: A promising approach for microencapsulation in controlled drug delivery

Spray drying has emerged as one of the most versatile and scalable microencapsulation techniques for developing controlled and targeted drug delivery systems. Its ability to convert liquid formulations into stable particulate systems in a single step has made it widely applicable for improving the stability, bioavailability, and release characteristics of therapeutic agents. This review critically examines the role of spray-dried microencapsulation in controlled drug delivery, with particular emphasis on formulation design, particle engineering, process optimization, and recent technological advancements. The review highlights that the performance of spray-dried microcapsules is primarily governed by the interplay between formulation composition and drying conditions. Appropriate selection of polymers, stabilizers, and processing parameters enables the production of particles with tailored size, morphology, encapsulation efficiency, and drug-release behavior. Recent innovations, including nano-spray drying, hybrid carrier systems, and stimuli-responsive polymers, have expanded the applicability of spray-dried formulations across oral, pulmonary, nasal, transdermal, and parenteral delivery routes while improving the protection and delivery of sensitive bioactive compounds. Despite these advances, several challenges continue to limit industrial translation, including thermal degradation of labile compounds, variability in particle formation, scale-up complexities, and regulatory constraints. Emerging approaches, such as QbD, advanced process modeling, AI-assisted optimization, and smart polymeric systems offer promising solutions to enhance reproducibility and therapeutic performance. Overall, spray-dried microencapsulation represents a robust and evolving platform for controlled and site-specific drug delivery. Continued integration of formulation science, process engineering, and advanced materials is expected to facilitate the development of next-generation drug delivery systems with improved efficacy, safety, and scalability.