Selection of Silica Type and Amount for Flowability Enhancements via Dry Coating: Contact Mechanics Based Predictive Approach.

Purpose: To investigate the effect of dry coating the amount and type of silica on powder flowability enhancement using a comprehensive set of 19 pharmaceutical powders having different sizes, surface roughness, morphology, and aspect ratios, as well as assess flow predictability via Bond number estimated using a mechanistic multi-asperity particle contact model.

Method: Particle size, shape, density, surface energy and area, SEM-based morphology, and FFC were assessed for all powders. Hydrophobic (R972P) or hydrophilic (A200) nano-silica were dry coated for each powder at 25%, 50%, and 100% surface area coverage (SAC).

Surface engineered excipients: III. Facilitating direct compaction tableting of binary blends containing fine cohesive poorly-compactable APIs.

Direct compaction tableting, a desired manufacturing option, is infeasible for blends containing fine cohesive poorly-compactable APIs at higher drug loadings. In this study, the feasibility of using fine, dry coated excipients is investigated instead of dry coating of the APIs, as was done previously. Avicel PH-105 (20.

Surface engineered excipients: II. Simultaneous milling and dry coating for preparation of fine-grade microcrystalline cellulose with enhanced properties.

A solventless process for simultaneously milling and dry coating microcrystalline cellulose (MCC) was investigated for producing fine excipients in five different sizes (∼20, 25, 30, 35, 40 µm) having high bulk density (BD), good flow function coefficient (FFC), and excellent compaction. Avicel PH-102, used as the starting material, was milled and coated with two grades of silicas, hydrophobic and hydrophilic (R972P and A200), using a fluid energy mill (FEM). Through judicious selection of the FEM feed rate, feeding pressure, and grinding pressure, five desired milled sizes were produced.

Surface engineered excipients: I. improved functional properties of fine grade microcrystalline cellulose.

Excipients with good flowability, bulk density as well as compaction properties are desired for use in tableting since they play important roles in formulation development and processing, including, handling, mixing, feeding and compaction. The objective of this paper is to examine the feasibility of using dry coating based surface modification of microcrystalline cellulose, Avicel PH-105, to produce an engineered fine grade (<30 μm) excipient that has all three desired properties. Using a material sparing high-intensity vibrational mixer, Avciel PH-105 is dry coated with 1 wt% Aerosil 200, selected due to its relatively higher dispersive surface energy and lower particle size amongst other silica choices.