AEROSIL®colloidal silicon dioxide has been used as a glidant to optimize the flow of powders since the earliest days of direct compression. The small AEROSIL® fumed silica particles “coat” the larger excipient and active ingredient particles, thus reducing van der Waals attractive forces between them. It can also absorb moisture being present on the surface of hygroscopic powders, thereby minimizing powder caking and clumping. These two effects help to prevent the formation of powder bridges and rat holes, as well as improving the flow through hoppers. Production of solid dosage forms on high-speed tablet presses or capsule filling equipment requires optimal flow of the dry precursor mixture. Used as a glidant, AEROSIL® colloidal silicon dioxide improves dosage uniformity and ultimately results in higher throughput.

Flow behavior of microcrystalline cellulose with (left) and without (right) AEROSIL® colloidal silicon dioxide

AEROSIL® colloidal silicon dioxide glidants help to improve tablet weight uniformity

The hydrophobic nature of AEROSIL® R 972 Pharma means the agglomerates are more easily broken apart compared to hydrophilic colloidal silicon dioxide types and therefore this product is especially suitable for short and/or low shear mixing processes. In addition to their excellent glidant properties in dry precursor mixtures, AEROSIL® products can also improve the properties of the finished product. For example, the hydrophilic products can in some cases increase the hardness of tablets without increasing the compaction force. This effect helps to maintain tablet stability without the increased disintegration times of denser tablets pressed at higher compaction force.

AEROSIL® colloidal silicon dioxide glidants help to improve tablet weight uniformity