Factorial design

Gastro retentive system can remain in the gastric region for several hours and hence prolongs the gastric residence time of drugs. The present research work was an attempt to formulate and in-vitro evaluate gastro retentive floating drug delivery system containing Gabapentin in the form of tablets using polymer like HPMC K100M and sodium bicarbonate, citric acid as gas generating agent. A 32 factorial design was applied systematically; the amount of HPMC K100M (X1) and amount of citric acid (X2) were selected as independent variables. The floating lag time, percentage drug release at 6 hr (Q6) and percentage drug release at 12 hr (Q12) were selected as dependent variables.  The tablets were prepared by direct compression method. The tablets were evaluated for the pre and post compression parameters such as weight variation, thickness, friability, hardness, drug content, in-vitro buoyancy studies, and in-vitro dissolution studies and results were within the limits. Hardness was found to be in the range 5.1±0.13 kg/cm2 to 7.1±0.36 kg/cm2, the percentage friability was in the range of 0.30% to 0.82% w/w, and tablets showed 99 to 101.10 %w/w of the labeled amount of Gabapentin indicating uniformity content. The in-vitro dissolution studies were carried out in a USP type-II apparatus in 0.1N HCl. Among all the formulations (GFT1 to GFT9) prepared, batch GFT7 was the best formulation which showed buoyancy lag time 5 sec  and the tablet remained buoyant for >12h. At all the strengths of the polymer tested HPMC K100M and citric acid gave relatively optimum release of gabapentin over 12 h when compared to other formulations. The tablets containing Gabapentin released 92.09 to 99.06% of drug release at the end of 12 hr by in-vitro drug release study. The in-vitro data is fitted in to different kinetic models and the best-fit was achieved with the Higuchi model. The optimized formulation GFT7 followed zero order release kinetics followed by non-Fickian diffusion.

Alitretinoin is used in treatment of AIDS related Kaposi’s sarcoma in concentrations of 0.1%. Alitretinoin is very effective but it causes skin erythema on the applied area. The Niosomes seems to be promising drug delivery in modern drug delivery systems. The main benefit over liposome is that the lipids are replaced by non-ionic vesicles and hence the preparation is totally non-antigenic. The non-ionic surfactants like SPANs and TWEENs are obtained from synthetic sources and hence the quality is maintained same all the time. The Alitretinoin was incorporated into niosomes using SPAN 60 and cholesterol. Various ratios of SPAN 60 and cholesterol were tried and optimized for the preparation of niosomes. Various process parameters were also optimized for the rotary flask evaporation method. The niosomal dispersion was incorporated in to carbopol 971NF gel. The gel was kept for 6 weeks accelerated stability studies. The niosomal dispersion was evaluated for various parameters like vesicle size, shape and morphology by Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM). In-vitro and ex-vivo studies were carried out. The drug release pattern from gel was evaluated on the basis of in-vitro studies and skin irritation studies on rat skin. The in-vitro study shows sustained release gel effects whereas the ex-vivo study shows no signs of irritation on the applied skin area.