Floating drug delivery systems (FDDS): A Review

Abstract

Floating drug delivery systems (FDDS) have emerged as an effective approach to improve the gastric residence time and bioavailability of drugs that are absorbed primarily in the upper gastrointestinal tract. This review focuses on the formulation and evaluation of floating tablets containing Acyclovir, an antiviral agent with limited oral bioavailability due to poor solubility and short biological half-life. The development of a gastroretentive floating tablet aims to achieve sustained drug release and prolonged gastric retention, ensuring improved absorption and therapeutic efficacy. Various polymers such as Hydroxypropyl Methylcellulose (HPMC), Carbopol, Ethyl Cellulose, and Sodium Alginate have been employed to modulate the swelling behavior, floating capacity, and release kinetics of the dosage form. The review emphasizes different formulation techniques like direct compression and wet granulation and discusses the influence of polymer type and concentration on tablet buoyancy and drug release profile. Evaluation parameters—including hardness, friability, floating lag time, total floating duration, swelling index, drug content uniformity, and in vitro dissolution studies—are critically analyzed. The optimized floating formulation of Acyclovir demonstrates enhanced gastric retention, controlled drug release, and improved bioavailability, making it a promising alternative to conventional oral dosage forms for effective antiviral therapy.

Keywords: Acyclovir; Floating tablet; Gastroretentive drug delivery system (GRDDS); Sustained release; HPMC.