No abstract

The potential of liquisolid systems to improve the dissolution properties of a water-insoluble agent (piroxicam) was investigated. In this study, physicochemical properties of piroxicam liquisolid tablets, effect of aging, and type of the carrier were also investigated. To this end, several liquisolid tablets formulations containing various ratios of drug: solvent and different carriers were prepared. X-ray crystallography, differential scanning calorimetry (DSC), and contact angle measurement were used for evaluation of physicochemical properties of piroxicam. Liquisolid compacts exhibited significantly higher drug dissolution rates, in different dissolution media, than compacts prepared by the direct compression technique. The results showed that enhanced dissolution rate of piroxicam liquisolid tablets was due to an increase in wetting properties and surface area of drug available for dissolution. To investigate the effect of aging on the hardness and dissolution rate of liquisolid compacts, the formulations were stored at 25 degrees C/75% relative humidity for 9 months. The results showed that aging had no significant effect on hardness or dissolution profile of liquisolid tablets. It was shown that Avicel had more liquid retention potential than other carriers, but there were no significant differences in the dissolution profiles between formulations. The results of DSC and X-ray crystallography did not show any changes in crystallinity of the drug and interaction between piroxicam and exipients (Avicel and silica) during the process.

Based on our findings, we suggest that the copolymer nanosuspension may favor the localized, controlled ocular delivery of MPA for the prevention of inflammatory symptoms in ocular diseases.

The potential of liquisolid systems to improve the dissolution properties of a water-insoluble agent (indomethacin) was investigated. In this study, different formulations of liquisolid tablets using different co-solvents (non-volatile solvents) were prepared and the effect of aging on the dissolution behaviour of indomethacin liquisolid compacts was investigated. To evaluate any interaction between indomethacin and the other components in liquisolid formulations, X-ray powder diffraction (XPD) and differential scanning calorimetry (DSC) were used. Dissolution test was carried out at two different pH, 1.2 and 7.2, to simulate the stomach or intestine fluid, respectively. The results showed that liquisolid formulations exhibited significantly higher drug dissolution rates at pH 1.2 and 7.2 compared to compacts prepared by the direct compression technique. The enhanced rate of indomethacin dissolution from liquisolid tablets was probably due to an increase in wetting properties and surface area of drug particles available for dissolution. In order to investigate the effect of aging on the hardness and dissolution rate of liquisolid compacts, the formulations were stored at 25°C /75% relative humidity for a period of 12 months. The results showed that aging had no significant effect on dissolution profiles of liquisolid tablets. Liquisolid compacts containing propylene glycol as vehicle produced higher dissolution rates in comparison with liquisolid compacts containing PEG 400 or Tween 80 of the same concentration. The DSC and XPD results showed no changes in crystallinity of the drug and interaction between indomethacin and excipients (Avicel and silica) during the process.

The present study was performed to design oral controlled delivery systems for the water-soluble drug, verapamil hydrochloride, using natural and semisynthetic polymers as carriers in the forms of 1-and 3-layer matrix tablets. Verapamil hydrochloride 1-layer matrix tablets containing hydroxypropylmethylcellulose, tragacanth, and acacia either alone or mixed were prepared by direct compression technique. 3-layer matrix tablets were prepared by compressing the polymers as release retardant layers on both sides of the core containing the drug. The prepared tablets were subjected to in vitro drug release studies. Tragacanth when used as the carrier in the formulation of 1-and 3-layer matrices produced satisfactory release prolongation either alone or in combination with the other 2 polymers. On the other hand, acacia did not show enough prolonging efficiency in 1-and 3-layer matrix tablets. The results also showed that the location of the polymers in the 3-layer tablets has a pronounced effect on the drug release. Kinetic analysis of drug release from matrices exhibiting sustained release indicated that release was predominantly attributable to the contribution made by Fickian diffusion, while the erosion/relaxation mechanisms had a minor role in the release.