Development and Optimization of Floating-Mucoadhesive Bilayer Tablets of Metformin Hydrochloride Using Quality by Design (QbD) Approach

AbstractFloating Drug Delivery System (FDDS) is an advanced gastroretentive drug delivery approachdesigned to prolong the residence time of drugs in the stomach and enhance theirbioavailability. Conventional oral dosage forms often face limitations such as rapid gastricemptying and reduced drug absorption in the gastrointestinal tract. The floating drug deliverysystem overcomes these challenges by remaining buoyant in the gastric fluid for an extendedperiod without affecting the gastric emptying rate. This system works by having a density lowerthan that of gastric fluids, allowing the dosage form to float on the stomach contents.FDDS is particularly beneficial for drugs that are primarily absorbed in the stomach or upperpart of the small intestine, drugs that are unstable in the intestinal environment, and drugs withlow solubility at higher pH levels. Various approaches are used to develop floating systems,including effervescent and non-effervescent techniques. Effervescent systems produce carbondioxide gas through the reaction of sodium bicarbonate with gastric acid, enabling the dosageform to float. Non-effervescent systems utilize swellable polymers such as hydroxypropylmethylcellulose (HPMC), carbopol, and sodium alginate to maintain buoyancy.Floating drug delivery systems provide several advantages, including improved drugbioavailability, reduced dosing frequency, sustained drug release, and enhanced patientcompliance. They are widely applied in the treatment of gastric disorders such as peptic ulcers,gastroesophageal reflux disease (GERD), and Helicobacter pylori infections. Despite thesebenefits, certain limitations such as variability in gastric retention time and the need forsufficient gastric fluid must be considered during formulation development.Overall, FDDS represents a promising strategy for controlled and site-specific drug delivery inthe stomach. Continuous research and technological advancements are expected to furtherimprove the efficiency and therapeutic effectiveness of gastroretentive floating drug deliverysystems.