Soft gelatin capsules (SGCs) are versatile and the most established oral dosage forms in pharmaceutical and nutraceutical product development due to their ability to facilitate the delivery of liquid and semisolid formulations, improve patient acceptability, and enhance the bioavailability of poorly water-soluble drugs. Over the years, SGC technology has evolved from a conventional encapsulation approach into an advanced drug delivery platform capable of supporting complex formulation strategies and therapeutic applications. Current review aims to comprehensively examines the historical development, classification, composition, physicochemical characteristics, advantages, and limitations of soft gelatin capsules, with particular emphasis on the functional roles of gelatin, plasticizers, fill materials, and auxiliary excipients in determining product quality and performance. This review further discusses compatibility assessment, formulation development, and stability considerations, together with critical aspects of industrial manufacturing, including rotary die encapsulation, ribbon formation, encapsulation mechanisms, drying processes, and moisture control. Quality-focused manufacturing approaches, such as Quality by Design (QbD), Process Analytical Technology (PAT), process optimization, and in-process quality control, are highlighted for their contributions to robust and efficient production. Important characterization methods, including mechanical evaluation, in vitro evaluation studies and stability studies, are also summarized. In addition, emerging applications involving lipid-based formulations, self-emulsifying drug delivery systems, controlled-release technologies, and bioavailability enhancement strategies are critically reviewed. Recent advancements in digital manufacturing, non-gelatin shell materials, nanotechnology-based systems, advanced sealing technologies, automation, and three-dimensional (3D) printing are discussed in the context of next-generation capsule development. Regulatory requirements, cGMP compliance, validation practices, sustainability considerations, intellectual property trends, and future industrial opportunities are also addressed, providing a comprehensive perspective on the current status and future direction of soft gelatin capsule technology. Keywords: Soft gelatin capsules; Rotary die encapsulation; Quality by Design (QbD); Lipid-based drug delivery systems; Regulatory compliance.
Palem et al. (Wed,) studied this question.