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Parmflow SiO2 (colloidal silicon dioxide) is a unique material for use as a flow-regulating agent. It is also used as an adsorbent, a viscosity-increasing agent, an emulsion-stabilizing agent and a tablet and capsule disintegrant. It is widely used in the pharmaceutical industry, in cosmetics, in food products and in nutritional supplements. The product Parmflow SiO2 has a very small particle size, resulting in a large specific surface area of 200 m2/g. Therefore, it is well suited to optimizing the flowability of powders. It also exhibits a high water-absorption capacity.
Parmflow SiO2 is prepared by flame hydrolysis and is a coagulation product of an SiO2 aerosol. Parmflow SiO2 is a highly purified form of silicon dioxide with a primary particle size of approximately 15 nm and a very large specific surface area of 200 m2/g. Therefore, it has an extremely low bulk density. The surface is stabilized through chemical adsorption of water in silanol groups. Due to these silanol groups (SiOH), Parmflow SiO2 is hydrophilic and can adsorb up to 40% water without liquefying.
Usage in Solid Formulations
Colloidal silicon dioxide is most commonly used as a flow-regulating agent in the manufacture of powders, capsules and tablets. Especially in the case of direct compression, where the flow characteristics of powder mixtures are often insufficient because of the active ingredients, Parmflow SiO2 can clearly increase the tableting performance, even at a concentration of around 0.5%.
The very small particles cover the particles of the active substances and excipients and can therefore reduce the van der Waals forces. Additionally, colloidal silicon dioxide adsorbs moisture and prevents the agglomeration of powders. Thus, Parmflow SiO2 decreases both cohesive and adhesive forces (for example at inlet funnels and feed shoes). The improved flow characteristics lead, among other things, to the optimization of the weight uniformity of capsules and tablets, a reduction in baking at the pressing tools and eventually to decreased friability and increased tensile strength of the tablets.
Parmflow SiO2 is suitable for isolating incompatible substances in a tableting mixture. In this case, sufficient mixing is required, so that Parmflow SiO2 particles are finely dispersed between the single API particles or crystals and can envelop them. Based on its attributes, Parmflow SiO2 is especially suitable as tablet and capsule disintegrant. If Parmflow SiO2 is used as an additive for a granulating liquid, the granules obtained are more hydrophilic.
On contact, water is attracted by the Parmflow SiO2 in the granules and transferred to the actual tablet disintegrant, such as Ultramyl, and the disintegration process is accelerated.
Parmflow SiO2 can adsorb up to 40% water and still retain its powder properties, making it an ideal adsorbent for many applications. Among other applications, Parmflow SiO2 is therefore used as an adsorbent in fine powders. Due to its hygroscopic nature, it can also be used to transfer liquids into dry powders. Furthermore, Parmflow SiO2 can be used as a drying agent and desiccant for hygroscopic substances.
Use in Liquid and Semi-Solid Formulations
Parmflow SiO2 is suitable for increasing the viscosity of liquids. The level of viscosity increase depends on the polarity of the liquid: polar liquids need a higher concentration (approximately 10-40% colloidal silicon dioxide) than non-polar liquids. The pH value also has an effect. If the pH value is above 7.5, the ability of colloidal silicon dioxide to increase the viscosity is attenuated and above a value of 10.7, colloidal silicon dioxide dissolves and loses its ability to increase viscosity.
Parmflow SiO2 can also be used at a concentration of 5-10% as a bulking agent for gels of liquid oils, such as cod liver oil, olive oil, etc. Combined with ingredients with a similar refractive index (Parmflow SiO2: 1.48), it leads to transparent gels. Above a concentration of 5%, as an additive in aqueous preparations, a thixotropic structure is obtained. Parmflow SiO2 is also used to thicken and stabilize topical formulations such as gels, liquids and creams.
Other Uses
Another important application of Parmflow SiO2 is as an additive in the lyophilization of nanocapsules and nanosphere suspensions.
In addition, Parmflow SiO2 can improve the drying process during the production of tablet coatings and prevent possible sedimentation of coating dispersions with a solid content. In low-solids coatings, e.g., colour pigments, 0.5-2.0% Parmflow SiO2 is usually sufficient to accelerate the drying process. When tablet cores are coated with a high-solids suspension, e.g., an API dispersion, 10-15% Parmflow SiO2 is recommended. However, the exact concentration should be determined empirically in tests.
As an additive in transdermal (membrane- and matrix-controlled) systems, Parmflow SiO2 also prevents the sedimentation of the ingredients in the matrix. This requires a concentration of 1-5%. In aerosols which are not used for inhalation, colloidal silicon dioxide also facilitates particle suspension, prevents agglomeration and minimizes the clogging of nozzles.
Storage and Handling
Parmflow SiO2 should be stored in tightly closed containers, due to its hygroscopic properties.
To prevent larger agglomerations of Parmflow SiO2, it is advisable to mix the total amount of Parmflow SiO2 with a small amount of other ingredients before sighting or sieving, and then to add the rest of the other ingredients. Please note: colloidal silicon dioxide should not be premixed with a lubricant such as magnesium stearate.
If one ingredient is considered critical with regard to flow characteristics or stickiness, it is advisable to mix the total amount of this excipient or API with the total amount of Parmflow SiO2 and add the remaining ingredients in a second step.
Parmflow SiO2 should never be used in preparations which contain acid-sensitive substances (for example amlodipine besylate, benzbromarone and diethylstilboestrol). In these cases, the large specific surface area and the remaining free acid groups in the silicon dioxide can lead to incompatibilities.
Colloidal silicon dioxide is approved as a food additive with the E-number E551.
Packing and storage
| Packing: | 10 kg paper bag with inner HDPE lining |
| Shelf life: | 2 years |
| Storage: | At ambient temperature, protected from moisture. |
Material Safety Data Sheet for Parmflow SiO2
 | Parmflow SiO2 - Specifications |
| Parmflow SiO2 - MSDS |