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In the past decade, the discovery of active pharmaceutical substances with high therapeutic value but poor aqueous solubility has increased, thus making it challenging to formulate these compounds as oral dosage forms. The bioavailability of these drugs can be increased by formulating these drugs as an amorphous drug delivery system. Use of porous media like mesoporous silica has been investigated as a potential means to increase the solubility of poorly soluble drugs and to stabilize the amorphous drug delivery system. These materials have nanosized capillaries and the large surface area which enable the materials to accommodate high drug loading and promote the controlled and fast release. Therefore, mesoporous silica has been used as a carrier in the solid dispersion to form an amorphous solid dispersion (ASD). Mesoporous silica is also being used as an adsorbent in a conventional solid dispersion, which has many useful aspects. This review focuses on the use of mesoporous silica in ASD as potential means to increase the dissolution rate and to provide or increase the stability of the ASD. First, an overview of mesoporous silica and the classification is discussed. Subsequently, methods of drug incorporation, the stability of dispersion and, much more are discussed.

Microcrystalline cellulose (MCC-102) is one of the most commonly used excipient in the pharmaceutical industry. For this research purpose, authors have developed a different technique to determine the end point for MCC-102 using water and isopropyl alcohol 70% (IPA) as granulating agent. Wet and dry granules obtained were characterized for their flow properties using the powder rheometer and thermal analysis. Powder rheometer was used to measure basic flowability energy (BFE), specific energy (SE), percentage compressibility, permeability and aeration. Thermal analysis includes effusivity and differential scanning calorimetry (DSC) measurements. BFE and SE results showed water granules requires high energy as compared to IPA granules. Permeability and compressibility results suggest IPA forms more porous granules and have better compressibility as compared to water granules. Hardness data reveals interesting phenomena in which as the amount of water increases, hardness decreases and vice-versa for IPA. Optimal granules were obtained in the range of 45-55% w/w. DSC data supported the formation of optimal granules. Empirical measurements like angle of repose did not reveal any significant differences between powder flow among various granules. In this paper, with the help of thermal effusivity and powder rheology we were able to differentiate between various powder flows and determine the optimal range for granule formation.

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Advancement in the discovery of drugs has led to many highly lipophilic compounds with very low water solubility. Amorphous solid dispersion is one of the emerging technologies to increase the solubility of these drugs. The stability of these systems is critical since the high energy system tends to recrystallize, which negates the benefits of these systems. In this paper, we are evaluating the use of colloidal silicon dioxide as a potential stabilizer to stabilize the amorphous solid dispersions. Two types of colloidal silicon dioxide are used: porous colloidal silicon dioxide -Syloid 244 Fp and nonporous fumed silica – Aerosil 200. These silicon dioxides have a high surface area. Two methods of incorporation are used to incorporate silicon dioxide into the solid dispersion. The spray drying method is used to make amorphous solid dispersion. It was found that porous silicon dioxide is better to increase stability as well as increasing dissolution rate and % release of the drug. The addition of silicon dioxide internally to the dispersion increases the dissolution rate, and the addition of silicon dioxide externally increases the stability of the solid dispersion. Keywords: colloidal silicon dioxide, stabilizer, amorphous solid dispersion, low water solubility