gastroretentive

Mucoadhesive dosage forms may be designed to enable prolonged retention at the site of application, providing a controlled rate of drug release for better therapeutic results. Mucoadhesive drug delivery systems are used to prolong the residence time of the dosage form at the site of application or absorption and to facilitate intimate contact of the dosage form with the underlying absorption surface to improve and enhance the bioavailability of drug. Some of the promising plymers that have been commonly used in these systems include polycarbophil, carbopol, lectins, chitosan, carboxymethylcellulose, pectin, carragenan, alginic acid, polylysine, polybrene, polyethylene glycol, polyvinyl pyrrolidone , dextran etc. Now  scientists are developing mucoadhesive micro and nanoparticulate systems by using  novel mucoadhesive polymers for better therapeutic results and site specific targeting with lesser side effects. Improvements in mucoadhesive based oral delivery and, in particular, the development of novel, highly-effective and mucosa-compatible polymers, are creating new commercial and clinical opportunities for delivery of narrow absorption window drugs at the target site to maximize their efficacy. This review is an effort to provide information on such mucoadhesive drug delivery systems that are developed for oral, buccal, nasal, rectal and vaginal routes for both systemic and local effect.

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.

  This present investigation deals with the design, development and evaluation of multiple unit beads containing gliclazide. The various gliclazide beads were prepared by ionotropic gelatin technique using sodium alginate, guargum and magnesium stearate in different ratios. These multiple unit beads were evaluated for size analysis, drug entrapment efficiency and in vitro drug release in simulated gastric fluids (pH 1.2) and phosphate buffer (pH 7.4). All these formulated showed sustained in vitro drug release in simulated gastric fluid over 6 hours. The gliclazide release was found to be more sustaining with the reduction of guargum content in the formulation .The drug release pattern of these multiple unit gliclazide beads (F-6 and F-7) were correlated well with first order model where F-1, F-4, F-5, F-8 and F-2 toF-3 was correlated well with Korsmeyer-Peppas model and Higuchi model with  non-Fickian diffusion mechanism. All the experimental results showed that the gliclazide loaded beads successfully sustain the drug release along with improve the oral bioavailability of candidate drug.