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Roller compaction was used to prepare a direct-compressed lactose excipient using crystalline α-lactose monohydrate. The effect of various roller compaction process parameters (compaction pressure, compaction repetition, and speed ratio) on the characteristics of compacted α-lactose monohydrate was investigated. Results were compared with data obtained using industrial spray-dried lactose and lactose samples with different degrees of crystallinity. XRPD analysis revealed that roller compaction reduced the crystallinity of α-lactose monohydrate, and the resulting material is similar to spray-dried lactose in behavior as a direct compression excipient. Roller compaction introduced desirable characteristics to the raw α-lactose monohydrate by inducing changes in crystallinity and particle morphology. Scanning electron microscopy results indicated that the compaction process converted some of the original torpedo-shaped crystals of α-lactose monohydrate into a more cylindrical shape with rounded edges. Compaction pressure and repetition of compaction have a significant effect on the modification of the crystallinity of the processed, raw α-lactose monohydrate. [ABSTRACT FROM AUTHOR]

The effect of cellulose ether polymer mixtures, containing both hydroxypropylcellulose (HPC) and hydroxypropylmethylcellulose (HPMC K15M or K100M), on ketoprofen (KTP) release from matrix tablets was investigated. In order to evaluate the compatibility between the matrix components, Raman spectroscopy, scanning electron microscopy (SEM), and X-ray powder diffraction (XRPD) experiments were performed. The results evidence the absence of significant intermolecular interactions that could eventually lead to an incompatibility between the drug and the different excipients. Formulations containing mixtures of polymers with both low and high viscosity grades were prepared by a direct compression method, by varying the polymer/polymer (w/w) ratio while keeping the drug amount incorporated in the solid dispersion constant (200 mg). The hardness values of different matrices were found within the range 113.8 to 154.9 N. HPLC analysis showed a drug content recovery between 99.3 and 102.1%, indicating that no KTP degradation occurred during the preparation process. All formulations attained a high hydration degree after the first hour, which is essential to allow the gel layer formation prior to tablet dissolution. Independent-model dissolution parameters such as t10% and t50% dissolution times, dissolution efficiency (DE), mean dissolution time (MDT), and area under curve (AUC) were calculated for all formulations. Zero-order, first-order, Higuchi, and Korsmeyer-Peppas kinetic models were employed to interpret the dissolution profiles: a predominantly Fickian diffusion release mechanism was obtained - with Korsmeyer-Peppas exponent values ranging from 0.216 to 0.555. The incorporation of HPC was thus found to play an essential role as a release modifier from HPMC containing tablets. [ABSTRACT FROM AUTHOR]

Twenty-two different graphite grades of the familiesnatural, synthetic,intercalated,expanded,amorphous,andturbostratic graphite, as well asplateletsandactivated carbon,were analyzed on their dispersibility inN-methylpyrrolidone, cyclohexylpyrrolidone and water-sodium cholate solution. They were characterized for their properties (grain size, density, purity, surface area, pH in water) and morphology. Thermogravimetric analysis, Raman spectroscopy studies, and electrical conductivity measurements were also used. XRPD followed by a Rietveld refinement provided information on the amounts of the rhombohedral (3R) and hexagonal (2H) phases for the crystalline part of the material and the interlayer distances. The properties of graphites favoring better dispersibility are: small grain size and bulk density, neutral pH in water. The electrical conductivity in inversely proportional to the RamanD-band intensity and is highest for the graphites with shortest interlayer spacing. TheD-,G- and2D-bands in the Raman spectra of graphites are in an exponential relation. [ABSTRACT FROM AUTHOR]

Thermal behavior of angiotensin II type 1 (AT1) receptor antagonist, Valsartan (VAL), was examined employing thermogravimetric analysis (TGA), standard differential scanning calorimetry (DSC) and temperature-modulated differential scanning calorimetry (TMDSC). The stability of VAL was measured by TGA from 25 to 600°C. Decomposition of Valsartan starts around 160°C. The DSC curve shows two endotherms, occurring around 80°C and 100°C, related to evaporation of water and enthalpy relaxation, respectively. Valsartan was identified by DSC as an amorphous material and it was confirmed by X-ray powder diffraction. The glass transition of fresh Valsartan appears around 76°C (fictive temperature). TMDSC allows separation of the total heat flow rate into reversing and nonreversing parts. The nonreversing curve corresponds to the enthalpy relaxation and the reversing curve shows changes of heat capacity around 94°C. In the second run, TMDSC curve shows the glass transition process occurring at around 74°C. Results from standard DSC and TMDSC of Valsartan were compared over the whole range of temperature. [ABSTRACT FROM AUTHOR]

Simvastatin is a hypocholestrolemic drug that is insoluble in water. Its low water solubility rate limits the pharmacological effects. The aim of this study was to improve the dissolution rate of simvastatin using spherical crystallization method. The drug was dissolved in boiling dichloromethane as the good solvent. This solution was added to 5°C water as the non-solvent. After sedimentation, isopropyl acetate was added as the bridging solvent. At the end the crystals were collected and dried for 12 h in a 50°C oven. The FTIR and DSC results showed no change in the drug after crystallization process. XRPD studies showed the sharp peaks are present in the diffractograms of spherical crystals with minor reduction in height of the peaks. The particle size of spherical aggregates was about 37 μm and the dissolution efficiency of simvastatin up to 60 min increased to about 2-fold in phosphate buffer solution containing 0.5% sodium dodecyl sulfate (pH 7) using the rotating paddle method. Spherical crystals showed enhanced solubility than untreated powder possibly due to partial conversion to amorphous form. Their dissolution rate at 60 min was still 4-fold of untreated powder when stored at 25°C and 84% relative humidity for one month. [ABSTRACT FROM AUTHOR]

The inhibition of the corrosive action of Acidithiobacillus thiooxidans on concrete specimens coated by functionalised zeolite-A containing 14% zinc and 5% silver by weight was studied. Uncoated concrete specimens, epoxy-coated concrete specimens (EP), and functionalised zeolite-A coated concrete specimens with epoxy to zeolite weight ratios of 3:1 (Z1), 2:2 (Z2) and 1:3 (Z3) were studied. Specimens were characterised by x-ray powder diffraction and field emission scanning electron microscopy for the identification of corrosion products and morphological changes. Biomass growth at the conclusion of the 32-day experiments was 4, 179 and 193 mg volatile suspended solids g-1 sulphur for the uncoated, EP and Z1 specimens, whereas that of Z2 and Z3 were negligible. In the uncoated, EP and Z1 specimens, sulphate production rates were 0.83, 9.1 and 8.8 mM SO42- day-1 and the specific growth rates, μ, were 0.14, 0.57 and 0.47 day-1, respectively. The corresponding values for Z2 and Z3 were negligible due to their bacterial inhibition characteristics. [ABSTRACT FROM AUTHOR]

In this work we examine the effect of storage conditions (moisture exposure) on the compression behavior of 2 grades of spray-dried lactose (Pharmatose DCL 11 and Pharmatose DCL 14) under 2 different circumstances. The first was to expose powder samples to moisture, then compress them. The second was to expose precompressed tablets to moisture. We clearly show that the effect of moisture exposure and amorphous content crystallization in spray-dried lactoses on compaction behavior depends on whether this moisture exposure takes place before or after compression. In addition, the impact of storage conditions depends on the grade of spray-dried lactose. [ABSTRACT FROM AUTHOR]

An experimental procedure adopted to prepare the recent Ferroelectric Glycine Phosphite (GPI) single crystal is presented. As the crystal solubility in water depends on temperature, single crystals were grown from fine seed crystals in a saturated solution by employing the slow cooling technique. Transparent, colourless crystals with habit morphology weighing about 8 gm were obtained with in a month. The same procedure was used to grow single crystals with Thiourea doped GPI (TUGPI). Powder X-ray diffraction studies as well as FTIR studies were carried out on both the crystals. The results are discussed in detail. [ABSTRACT FROM AUTHOR]

Proper formulation is an important aspect of any dosage form design. As a part of preformulation studies, differential scanning calorimetry (DSC) was used to investigate the physicochemical compatibility between Carbamazepine and various excipients commonly used in tablet manufacturing, supported by Fourier transform infrared (FTIR) and x-ray powder diffraction (XRPD) studies. Compatibility studies were conducted on samples kept at room temperature and at an elevated temperature of 55° C for 3 weeks. Carbamazepine was found to be compatible with all lactose-based components, such as Granulac 230®, Flowlac 100®, and Microcelac 100®. Differential scanning calorimetry studies indicated incompatibility with mannitol, microcrystalline cellulose, starch, and stearic acid. However, XRPD and FTIR studies implied that all the above excipients are compatible with Carbamazepine. X-ray powder diffraction demonstrated incompatibility with stearic acid for samples stored at 55°C for 3 weeks, indicative of formation of a solid solution. Thus, DSC being a thermal method of analysis should not be used singly to detect any inherent incompatibility. It has to be supported sufficiently by other non-thermal techniques, such as XRPD and FTIR. [ABSTRACT FROM AUTHOR]