Famotidine is a histamine H2-receptor antagonist. It is widely prescribed in the treatment of gastric ulcers, duodenal ulcers, Zollinger-Ellison syndrome, and gastroesophageal reflux disease in doses ranging from 10 to 80 mg (1). The low bioavailability (40–45%) and short biological half-life (2.5–4.0 h) of famotidine following oral administration favors the development of a sustained-release formulation. Gastroretentive drug delivery systems can be retained in the stomach, and thus can help improve the oral sustained delivery of drugs that have an absorption window in a particular region of the gastrointestinal tract. These systems facilitate continuous release of a drug before it reaches the absorption window, thus ensuring optimal bioavailability (2).
The oral treatment of gastric disorders with an H2 receptor antagonist such as famotidine or ranitidine in combination with antacids promotes local delivery of these drugs to the receptor of parietal cell wall. Local delivery also increases the bioavailability of the stomach-wall receptor site and increases the efficacy of drugs to reduce acid secretion. Hence, this principle may improve systemic as well as local delivery of famotidine, which would efficiently reduce gastric-acid secretion (3).
Several approaches can be used to prolong gastric retention time, including floating drug delivery systems (i.e., hydrodynamically balanced systems), swelling and expanding systems, polymeric bioadhesive systems, modified-shape systems, high-density systems, and other delayed gastric-emptying devices (4–10).A dosage form that delivers famotidine in the stomach as a floating drug delivery system is one approach. A floating drug delivery system can be designed by incorporating at least one porous structural element that is less dense than gastric juice (11). Research also has been done in making floating (effervescent-type) drug delivery system for gastroretention using famotidine (12). A new type of multiparticulate floating drug delivery system consists of a highly porous carrier material (foam powder), drug, and polymer as low density microparticles (13–14). The material has a low density, large cavities interconnected by smaller pores (which give it a highly permeable structure), good compressibility, and good flowability. This article describes the development of gastroretentive matrix tablets of famotidine to increase therapeutic efficacy, reduce frequency of administration, and improve patient compliance. The study includes the use of low-density polymers for their high porosity and floating efficiency.