sustained release

ABSTRACTIn-Situ buffer formulation contain agents which immediately buffer the internal environment of the body and increases the stability of acid labile drugs inside the body. Here this approach is used for making combination capsule formulation to reduce the side effects of Nonsteroidal anti-inflammatory drugs. Pantoprazole is an acid labile drug which is very useful for the prevention and treatment of NSAID related gastric ulcer, so to reduce its side effects this approach was used. In this Indomethacin is used as Nonsteroidal anti-inflammatory drugs. For this purpose, macroenvironment buffering method was used. Based on their acid neutralizing capacity the best buffering combination was selected. In this method immediate release excipients or superdisintegarnts (SSG & CCS) whereas rate retarding polymers (Guar gum, Xanthan gum & ethyl cellulose) were added in the formula.  Ex vivo permeation study was performed by using Non-everted intestinal sac method in selected optimized batch. For optimization full factorial 23 design was used along with mathematical models. Prepared optimized formulation was compared with marketed formulation. Final pH from optimized formulation was found to be 5 to 6. The prepared optimized capsule is having 98.86% immediate release of pantoprazole sodium sesquihydrate upto 30 min and 99.84% sustain release of indomethacin upto 12 hrs. The prepared formulation showed immediate release of stable pantoprazole sodium sesquihydrate (due to the presence of in-situ buffering agents inside the capsule) along with the sustained release Indomethacin with very less adverse effects. Keywords: Stable pantoprazole sodium sesquihydrate, sustained release, macroenvironment, Ex vivo permeation.

The present study was aimed to develop generic formulation of sustained release matrix tablets of Nevirapine using TSP as a hydrophilic polymer. The tamarind seed polysaccharide was extracted from tamarind kernel powder and this polysaccharide was utilized in the formulation of matrix tablets containing Nevirapine by wet granulation technique and evaluated for its drug release characteristics. TSP is a hydrophilic and rate controlling polymer. Granules were prepared and evaluated for loose bulk density, tapped density, compressibility index and angle of repose, shows satisfactory results. Formulation was optimized on the basis of acceptable tablet properties (hardness, friability, drug content and weight variations.), in vitro drug release and stability studies. All the formulations showed compliance with pharmacopoeial standards. The in vitro release study of matrix tablets were carried out in phosphate buffer pH 7.4 for 12hr. Among all the formulations, F5 shows 99.062% better controlled release at the end of 12 hr. The results indicated that a decrease in release kinetics of the drug was observed by increasing the polymer concentration. The release data was fitted to various mathematical models such as, Higuchi, Krosmeyer-Peppas, first-order, and zero order to evaluate the kinetics and mechanism of the drug release. The drug release of optimized formulations F5 follows Krosmeyer-Peppas kinetics and the mechanism was found to be diffusion coupled with erosion (non-Fickian diffusion). The stability studies were carried out according to ICH guideline which indicates that the selected formulation were stable.

A pH sensitive hydrogel using Carbopol-PEG 400 combination was prepared and loaded with amoxicillin trihydrate drug to study its sustained release. The hydrogel prepared was of physical nature. Two types of hydrogel were prepared with and without drug. The drug used was amoxicillin trihydrate. This drug is used to treat peptic ulcer in gastrointestinal tract. This drug becomes unstable in acidic environment of stomach. A pH sensitive hydrogel can be designed which can retain the drug in the polymer core at low pH values and release it at high pH value environment like gastrointestinal tract. Characterization of the hydrogel was done by SEM and FTIR and performance was studied by swelling method and in vitro drug release. FTIR studies gave the backbone structure of hydrogel carrying the drug. The surface morphology study by SEM showed that the prepared hydrogel was porous in nature. The swelling studies showed that the hydrogel swelled more in basic medium as the components were anionic in nature. The release profile showed 83.93% sustained drug release after 10hours. The carbopol-PEG400 hydrogel is suitable for the delivery of amoxicillin trihydrate as the drug is not stable in the stomach and can be delivered satisfactorily to the intestine where the pH is favourable.