Use of calcined Mg–Al–hydrotalcite to enhance the stability of celecoxib in the amorphous form

Use of calcium carbonate as an excipient for release of poorly water soluble drugs: The case of carbamazepine

Carbamazepine (CBZ) is a poorly water soluble drug owing to the Biopharmaceutic Classification System (BCS) class II. It is characterized by a variable bioavailability and by the presence of different polymorphs. In this paper the effects of CaCO₃ on the physicochemical properties of CBZ and its solubility and release were evaluated. CaCO₃ is a naturally non-toxic biomineral and was chosen because it is a safe, cheap and eco-friendly excipient able to dissolve in an acidic environment. Composites with different CBZ loadings were prepared by ball milling and antisolvent method. The composites were characterized by X-ray powder diffraction, differential scanning calorimetry analysis and attenuated total reflectance FT-IR which revealed that both the presence of CaCO₃ and the preparation procedure affect the polymorphic form crystallinity and intermolecular interactions among the drug molecules. Scanning electron microscopy showed that small drug crystals with different crystalline forms were deposited on the surface of the CaCO₃ particles. Solubility and dissolution tests showed an increase in the apparent solubility of CBZ and improved drug release. These results demonstrated that CaCO₃ affected the drug release properties likely due to its pH-sensitive characteristics.

Celecoxib confinement within mesoporous silicon for enhanced oral bioavailability

We investigate the physicochemical characteristics of celecoxib (CEL) entrapped within particles of an oxidized porous silicon matrix (pSiox); determine the oral dose response of CEL compared to pure drug and innovator formulation; develop in vivo-in vitro correlation (IVIVC). CEL was loaded into a pSiox matrix by solvent partitioning, with the physical state of the CEL characterized by FTIR, DSC, TGA and XRD, and correlated with in vitro dissolution behavior. Single dose pharmacokinetic parameters of orally dosed CEL were determined in fasted rats for aqueous suspensions of pure CEL, Celebrexr and CEL-pSiox microparticles. Physicochemical testing of CEL-pSiox formulation confirmed the entrapment of CEL within porous nanostructure in an amorphous or non-crystalline form. CEL-pSiox demonstrated superior pharmacokinetics compared with CEL particles or Celebrexr, i.e. increased absolute bioavailability (96.2% vs. 65.2% vs. 88.1%), increased C

Formulation of intelligent tablets with an antacid effect

Matrix systems with a local antacid effect were produced in this study. Aluminium hydroxide and magnesium trisilicate in constant concentrations were used as active agents. Eudragit E PO was applied as a matrix former and sodium bicarbonate as a disintegrant (third antacid component), in different ratios. Their effects on the properties of the tablets were studied. Such formulated systems must be insoluble if the pH of the stomach is less acidic, but a rapid disintegration must occur if necessary. It can be concluded that Eudragit E PO in appropriate composition can ensure tablets with pH-dependent disintegration. Its binding effect allows tablet making from the elastic active component. The liberation of antacid materials from this system is controlled. If the pH reached 2.5, the erosion of the tablet was reduced. In contrast with expectations, the application of poorly compressible and effervescent sodium bicarbonate increased the time for disintegration of the tablets, because of its extended alkalizing effect around the tablet. This system with this acrylic component is appropriate to produce a controlled-release local antacid preparation.