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.
The following materials were used: famotidine (lot 1160573, Torrent Pharmaceuticals, Chhatral, Kalol, India); low-density
powder poly(styrene-divinyl benzene) copolymer [PSDVB] (lot 061117, Polygenetics, Los Gatos, CA); xanthan 150 (lot 8E0087K)
and Klucel HXF (lot 4653, Cadila Pharma, Dholka, India); chitosan (lot 6843, Central Institute of Fisheries Technology, Cochin,
Kochi, India); psyllium (lot 818, Atlas Industries, Shiddhpur, Gujarat, India); hydroxypropyl methyl cellulose K15M (lot 1240150)
and hydroxypropyl methyl cellulose K100M (lot 1240225) (Torrent Pharmaceuticals); and sodium alginate, hydrochloric acid,
dicalcium phosphate, talc, and magnesium stearate (SD Fine Chemicals, Mumbai, India). All ingredients were of analytical grade.
Table I: Compositions of the investigated tablets (all quantities are given in mg) .