Abstract. In order to improve the bioavailability of the antidepressant drug, venlafaxine hydrochloride, in situ mucoadhesive thermoreversible gel, was formulated using Lutrol F127 (18%) as a thermo gelling polymer. Mucoadhesion was modulated by trying carbopol 934, PVP K30, HPMC K4M, sodium alginate, tamarind seed gum, and carrageenan as mucoadhesive polymers. Results revealed that as the concentration of mucoadhesive polymer increased the mucoadhesive strength increased but gelation temperature decreased. Formulation was optimized on the basis of clarity, pH, gelation temperature, mucoadhesive strength, gel strength, viscosity, drug content, diffusion through sheep nasal mucosa, histopathological evaluation of mucosa, and pharmacodynamic study in rats. Final formulation T5 containing 18% Lutrol F127 and 0.3% PVP K30 was considered as an optimized formulation. T5 released 97.86±0.073% drug in 150 min with a flux of 0.1545 mgcm −2 min −1 and gelation temperature 31.17±0.30°C. Histopathological evaluation of nasal mucosa revealed that T5 formulation was safe for nasal administration as it caused no damage to nasal epithelium. From the results of pharmacodynamic study, mainly forced swim test (FST), it was concluded that venlafaxine hydrochloride was more effective as an antidepressant by nasal route as in situ gel nasal drops in comparison to oral administration of equivalent dose.

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In recent years, gastroretentive drug delivery system (GRDDS) has gained researcher’s interest in the field of oral drug delivery. Various GRDDS approaches can be utilized to retain the dosage forms in the stomach and to release the drug slowly for an extended period of time. GRDDS can be used to prolong the residence time of delivery system in the stomach. This results in targeting of drug release at a specific site for the systemic or local effects. GRDDS can be used to overcome challenges associated with conventional oral dosage forms and to release the drug at a specific absorption site to improve bioavailability of particular drug substance. The challenges include fast gastric emptying of the dosage form which results in the poor bioavailability of the drug. Prolongation of the retention of drugs in stomach those having low solubility at high intestinal pH improves the solubility of drugs. GRDDS has proved to be effective in systemic actions as well as in local actions to treat gastric or duodenal ulcers. Local activity in the upper part of the small intestine can be obtained by improving the residence time of delivery system in the stomach. The system is useful for drugs which are unstable in the intestine or having a low solubility/permeability in the small intestine. Various GRDDS approaches include high density (sinking) systems, low-density (floating systems), mucoadhesive, expandable, unfoldable, superporous hydrogel systems, and magnetic systems.

The aim of the present research work was to systemically device a model of factors that would yield an optimized release modulating dosage form of an anti-hypertensive agent, losartan potassium, using response surface methodology by employing a 3-factor, 3-level Box-Behnken statistical design. Independent variables studied were the amount of the release retardant polymers – aminated fenugreek gum (X1), aminated tamarind gum (X2) and aminated xanthan gum (X3). The dependent variables were the burst release in 15 min (Y1), cumulative percentage release of drug after 60 min (Y2) and hardness (Y3) of the tablets with constraints on the Y2 = 31–35%. Statistical validity of the polynomials was established. In vitro release and swelling studies were carried out for the optimized formulation and the data were fitted to kinetic equations. The polynomial mathematical relationship obtained Y2=32.91-2.29X1-5.68X2-0.97X3+0.20X1X3-0.005X2X3-0.92X12-1.89X22 explained the main and quadratic effects, and the interactions of factors influencing the drug release from matrix tablets. The adjusted (0.9842) and predicted values (0.9600) of r2 for Y2 were in close agreement. Validation of the optimization study indicated high degree of prognostic ability of response surface methodology. The Box-Behnken experimental design facilitated the formulation and optimization of release modulating matrix systems of losartan potassium.

Microsponges drug delivery system composed of porous microsphere. They are tiny sponges-like spherical particles with a larger porous surface. Morever they may enhance stability, reduce side effect and modify drug release favorably. Microsponges technology has many favorable characteristics, which make it a versatile drug delivery system. Microsponge system are based on microscopic, polymer-based microsphere that can suspend or entrap a wide variety of substance, and it can be incorporated into a formulated product such as a gel, cream, liquid or powder. The outer surface is typically porous, allowing a sustained floe of substance out of the sphere. Microsponges are designated to deliver a pharmaceutical active ingredient efficiently at the minimum dose and also to enhance stability, reduce side effect, and modify drug release.