Abstract. Drugs that have narrow absorption window in the gastrointestinal tract (GIT) will have poor absorption. For these drugs, gastroretentive drug delivery systems offer the advantage in prolonging the gastric emptying time. Swellable, floating, and sustained release tablets are developed by using a combination of hydrophilic polymer (hydroxypropyl methylcellulose), swelling agents (crospovidone, sodium starch glycolate, and croscarmelose sodium) and effervescent substance (sodium bicarbonate). Formulations are evaluated for percentage swelling, in vitro drug release, floating lag time, total duration of floating, and mean residence time (MRT) in the stomach. The drug release of optimized formulation follows the Higuchi kinetic model, and the mechanism is found to be non-Fickian/anomalous according to Krosmeyer-Peppas (n value is 0.68). The similarity factor (f 2 ) is found to be 26.17 for the optimized formulation, which the release is not similar to that of marketed produced (CIFRAN OD®). In vivo nature of the tablet at different time intervals is observed in the radiographic pictures of the healthy volunteers and MRT in the stomach is found to be 320±48.99 min (n=6). A combination of HPMC K100M, crospovidone, and sodium carbonate shows the good swelling, drug release, and floating characters than the CIFRAN OD®.

Abstract. The study aim was concerned with formulation and evaluation of bioadhesive buccal drug delivery of tizanidine hydrochloride tablets, which is extensively metabolized by liver. The tablets were prepared by direct compression using bioadhesive polymers such as hydroxylpropyl methylcellulose K4M, sodium carboxymethyl cellulose alone, and a combination of these two polymers. In order to improve the permeation of drug, different permeation enhancers like beta-cyclodextrin (β-CD), hydroxylpropyl beta-cyclodextrin (HP-β-CD), and sodium deoxycholate (SDC) were added to the formulations. The β-CD and HP-β-CD were taken in 1:1 molar ratio to drug in formulations. Bioadhesion strength, ex vivo residence time, swelling, and in vitro dissolution studies and ex vivo permeation studies were performed. In vitro release of optimized bioadhesive buccal tablet was found to be non-Fickian. SDC was taken in 1%, 2%, and 3% w/w of the total tablet weight. Stability studies in natural saliva indicated that optimized formulation has good stability in human saliva. In vivo mucoadhesive behavior of optimized formulation was performed in five healthy male human volunteers and subjective parameters were evaluated.KEY WORDS: bioadhesive buccal tablets; in vitro evaluation; in vivo mucoadhesive behavior; permeation enhancers; stability studies in natural saliva; tizanidine hydrochloride.

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Korni et al.: Liquisolid Technique to Enhance Dissolution Rate of OlanzapineThe present work was aimed at enhancing the dissolution rate of olanzapine, an antipsychotic agent using the liquisolid technique. Liquisolid system is an innovative technique used for enhancing dissolution rate and bioavailability of poorly soluble drugs. A mathematical model was utilized to formulate liquisolid tablets. Two non-volatile liquids were used in the design of liquisolid tablets, Tween 80 and propylene glycol. The effect of formulation parameters, such as drug:non-volatile liquid ratio and carrier:coating ratio was observed. Microcrystalline cellulose and silica were used as carrier and coating materials, respectively. All liquisolid formulations showed higher drug dissolution rate than directly compressible tablets and marketed tablets. Differential scanning calorimetry revealed that the drug has got solubilised in the liquid vehicle, which was further supported by x-ray diffraction studies and scanning electron microscopy. Infrared spectroscopy studies indicated the absence of incompatibility between drug and non-volatile solvents. This study shows that liquisolid technique is a promising alternative for improvement of dissolution rate of water-insoluble drug.