floating drug delivery

Gastro retentive systems can remain in the gastric region for several hours and hence prolongs the gastric residence time of drugs and improve the bioavailability. The aim of this project was to develop sustained release floating matrix tablet for hydroalcoholic extract of neem leaves using psyllium husk as release controlling polymer along with synthetic polymer HPMC K100 M and sodium bicarbonate as gas generating agent. The tablets were prepared by direct compression method. Seven different formulations A1 to A7 were prepared by varying the concentration of psyllium husk, HPMC K100 M and sodium bicarbonate. Tablets were evaluated for pre and post compression parameters like tablet thickness, hardness, weight variation, drug content, friability, floating lag time and in vitro drug release. Results for angle repose, swelling index, weight variation, drug content, thickness, hardness, % friability for all the formulations were found to be in acceptable limit. In vitro drug release was observed for 12 hours and all the tablet formulations followed zero-order kinetics and/ or Korsemeyer-Peppas model in drug release. The formulations were optimized on the basis of buoyancy time and in vitro drug release. The optimized formulation was found to be A4 with 98.77% in vitro drug release in 12 h and 212 seconds buoyancy time. The BaSO4 tagged formulation, similar to formulation A4 was tested in in vivo gastric retention study in rabbits. It was observed that formulation kept floating in the stomach region till 10 hours. Formulations containing combination of psyllium husk and HPMC K100M with sodium bicarbonate as gas generating agent can be a promising way for formulating gastroretentive drug delivery systems.

Gastro retentive drug delivery is an approach to prolong gastric residence time, thereby targeting site-specific drug release in the upper gastro intestinal tract (GIT) for local and systemic effect. The present study has been a satisfactory attempt to formulate floating drug delivery system of Valacyclovir, an orally administrated antiviral drug with a view of improving its oral bioavailability and giving sustained release of the drug. In present study design expert trial 8.0.6.1 software is used for designing of experiment. In central composite design based on response surface methodology yielded nine experimental runs. These nine formulations are evaluated for precompressional parameters like bulk density, tapped density, angle of repose and carr’s index. Formulations are also evaluated for postcompressional parameters like hardness, thickness, weight variation etc. all the formulations shows results in the acceptable range. All preliminary formulations are subjected to invitrobouyancy and dissolution study. The data obtained from the in vitro release study was fit to various kinetic models to explain the release profile of the drug. Kinetic models used were zero and first-order equations, Krosmeyersand peppas and Higuchi models. Based on results obtained from the prelimimary formulations five optimized formulations are selected and validated. Short-term stability study was done for optimized formulations.

The present study aims at the formulation of a floating drug delivery system of an antiulcer drug nizatidine using different grades of HPMC (K100, K4M, K15M & K100M) and an effervescent agent i.e. sodium bicarbonate. It was found that the release rate of nizatidine from tablet formulations prepared from HPMC K100LV was very high as compared to that from formulations containing higher viscosity grades namely K4M, K15M and K100M. In the current study, it was also found that overall rate of drug release tends to decrease with increase in concentration of HPMC. These observations are in agreement with the results reported in literature i.e. with the increase in polymer concentration and viscosity grade, the viscosity of gel layer around the tablet also increases leading to enhanced diffusional path length for the drug to follow and thus limits the release of active ingredient.