Buoyancy

Gastroretentive drug delivery systems (GRDDS) have emerged as an advanced approach to overcome the limitations of conventional oral dosage forms by prolonging gastric residence time and improving drug bioavailability. The objective of these systems is to remain buoyant in gastric fluid for extended periods, allowing controlled release of drugs and enhanced absorption of medications with limited absorption windows. Floating tablets achieve buoyancy using low-density excipients, such as gas-generating substances like sodium bicarbonate, or swellable polymers like hydroxypropyl methylcellulose (HPMC). Formulation strategies generally employ polymeric matrices, effervescent components, or coating technologies to regulate release kinetics and enhance stability. Evaluation parameters, such as floating lag time, total floating duration, and in vitro and in vivo correlation, are essential for assessing system performance. GRDDS can improve the therapeutic efficacy of medicines used in gastrointestinal disorders and those requiring localized gastric delivery. Despite significant advancements, variability in gastric motility and physiological factors limit the reproducibility and scalability of formulations. This review consolidates current progress and identifies future directions for optimized gastroretentive floating tablet technology.

One of the most feasible approaches for achieving prolonged and predictable drug delivery profiles in gastrointestinal tract is to control the Gastric Residence Time (GRT) using gastro retentive dosage forms (GRDFs) that offer a new and better option for drug therapy. Oral delivery of drugs is by far the most preferable route of drug delivery. Oral-rate controlled drug delivery systems have an important area among novel drug delivery system. But these oral sustained release drug delivery systems suffer greatly due to their short gastric residence time/ gastric emptying time. Whereas prolonged gastric residence increases duration of drug release, reduces drug waste, and improves drug solubility in gastric pH. In order to overcome these drawbacks novel dosage forms that can be retained in the stomach for a prolonged and predictable period of time were discovered and they successfully exists today as gastro retentive dosage forms, in academic and industrial research groups. The objective of our review is to compile the recent advancements and literatures regarding the novel dosage form i.e. the floating drug delivery systems (FDDS) that can be retained in the stomach for a prolonged period of time and gives therapeutic action in a predetermined manner. Several approaches are currently utilized in the prolongation of the GRT, including floating drug delivery systems (FDDS), swelling and expanding systems, polymeric bioadhesive systems, high-density systems, modified-shape systems and other delayed gastric emptying devices. In this review, current & recent developments of Stomach Specific FDDS are discussed. The recent developments of FDDS including the physiological and formulation variables affecting gastric retention, approaches to design single-unit and multiple-unit floating systems, and their classification and formulation aspects are covered in detail.

The aim of writing this review is to put a light on the recent trends in development of Drug loaded Beads. Drug loaded beads are gastro retentive drug delivery systems based on multi Unit approach and are prepared to obtain prolonged or controlled drug delivery, to improve bioavailability, stability and target drug to specific sites. These are Spherical in shape and approximately 1.5 mm in diameter. These can be prepared by various methods like ionotropic gelation, hydrogel embedment, solvent evaporation and Melt Solidification by using different polymers. Promising enhancement in bioavailability and site specificity has been achieved by drug loaded beads.

Gastric emptying is a complex process and makes in vivo performance of the drug delivery systems uncertain. Floating Bilayer drug delivery system is combined principle of bilayer tablet as well as floating mechanism. Floating drug delivery system provides advantages local delivery to specific region like stomach and proximal small intestine and it’s also shows better bioavailability and improved therapeutic activity. Floating Bilayer tablet is suitable for sequential release of two drugs in combination, separate two incompatible substances and also for sustained release tablet in which one Layer is immediate release as initial dose and second layer is maintenance dose. The purpose of this paper is to review the concept of Floating Bilayer drug delivery systems with the recent literature and current technology used in the development of Floating Bilayer drug delivery system as well as summarizes evaluation method and applications of various floating dosage forms. Key words: - Bilayer Floating drug delivery systems, Gastric residence time, Swelling index, Buoyancy