Neural network: an instrument to study flow and packing properties of pharmaceutical powders

In the present study five brands of microcrystalline cellulose (Ph101, Vivapur, Ph 301, Emcocel and Prosolv), three brands of Crospovidone (XL, XL-10 and INF) and pregelatinized Starch were mixed with 2% w/w of Aerosil 200, Aerosil R972 (two different kinds of colloidal silicon dioxide) or Mg stearate, to obtain 27 distinct mixtures. Flow rate, bulk and tapped density of mixtures were measured and tablets were prepared

Pharmaceutical nanocrystals: production by wet milling and applications

Nanocrystals are regarded as an important nanoformulation approach exhibiting advantages of increased dissolution and saturation solubility with chemical stability and low toxicity. Nanocrystals are produced in the form of nanosuspensions using top-down (e.g., wet milling or high pressure homogenization) and bottom-up methods (e.g., antisolvent precipitation). Wet milling is a scalable method applicable to drugs with different physicochemical and mechanical properties. Nanocrystalline-based formulations, either as liquid nanosuspensions or after downstream processing to solid dosage forms, have been developed as drug delivery systems for various routes of administration (i.e., oral, parenteral, pulmonary, ocular, and dermal). In this review, we summarize and discuss the features, preparation methods, and therapeutic applications of pharmaceutical nanocrystals, highlighting their universality as a formulation approach for poorly soluble drugs

Inertial effects on thin-film wave structures with imposed surface shear on an inclined plane

This study provides an extended approach to the mathematical simulation of thin-film flow on a flat inclined plane relevant to flows subject to high surface shear. Motivated by modelling thin-film structures within an industrial context, wave structures are investigated for flows with moderate inertial effects and small film depth aspect ratio, epsilon. Approximations are made assuming a Reynolds number, Re ~ O(1/epsilon), and depth-averaging used to simplify the governing Navier-Stokes equations. A parallel Stokes flow is expected in the absence of any wave disturbance and a generalisation for the flow is based on a local quadratic profile. This approach provides a more general system which includes inertial effects and is solved numerically. Flow structures are compared with studies for Stokes flow in the limit of negligible inertial effects. Both two-tier and three-tier wave disturbances are used to study film profile evolution. A parametric study is provided for wave disturbances with increasing film Reynolds number. An evaluation of standing wave and transient film profiles is undertaken and identifies new profiles not previously predicted when inertial effects are neglected

Powder Compaction: Compression Properties of Cellulose Ethers

Effective development of matrix tablets requires a comprehensive understanding of different raw material attributes and their impact on process parameters. Cellulose ethers (CE) are the most commonly used pharmaceutical excipients in the fabrication of hydrophilic matrices. The innate good compression and binding properties of CE enable matrices to be prepared using economical direct compression (DC) techniques. However, DC is sensitive to raw material attributes, thus, impacting the compaction process. This article critically reviews prior knowledge on the mechanism of powder compaction and the compression properties of cellulose ethers, giving timely insight into new developments in this field

Computer-aided estimation of acetone, methyl acetate, and chloroform diffusion coefficients in poly(vinyl acetate)

The diffusion coefficients of acetone, methyl acetate, and chloroform in amorphous poly(vinyl acetate) are estimated using the solvent evaporation method. The evaporation process from polymer solutions, cast in the form of thin films, is studied as a numerical experiment. The process is modeled as a coupled heat and mass transfer problem with a moving boundary. Lattice fluid (LF) thermodynamics is used to describe polymer-solvent system volumetric properties and to derive appropriate expressions for solvents' chemical potentials. The resulting nonlinear system of governing equations is solved with the Galerkin finite element method. The estimated diffusion coefficients are in satisfactory agreement with reported data