Unveiling Neusilin® US2’s Prowess: Resolving Oily API Challenges in Contrast to Other Common Excipients

Neusilin® US2 by Fuji Chemical Industries is a synthetic, amorphous form of Magnesium Aluminometasilicate with a neutral pH that can be used in both direct compression and wet granulation of solid dosage forms. Oily APIs affect flowability, compressibility, and disintegration times, thereby posing problems to formulators.

Due to its large surface area and porous nature, Neusilin® US2 adsorbs high loads of oil and can be compacted into high-quality tablets. In this newsletter, we demonstrate the prowess of Neusilin® US2 in solving the problems related to the oily nature of APl’s when compared to other common excipients.

Neusilin® in contrast to Colloidal Silicon Dioxide and Micronized Silicon Dioxide

Formulation Example:

30g of boiled linseed oil was diluted with 60g of ethanol and mixed well before loading onto 66g of Neusilin® US2, Colloidal silicon dioxide, and Micronized silicon dioxide (30% oil load). In another set, 40g of boiled linseed oil was diluted with 80g of ethanol before loading onto 569 of Neusilin® US2 (40% oil load). The mixture was dried in an oven at 50°C overnight to remove ethanol. The browning observed with both the silica grades is thought to result from the oxidation of the boiled linseed oil due to surface acidity of silica. The neutral surface of Neusilin®, on the other hand, helped suppress this reaction, and no dark coloration was thus seen with Neusilin®.

Characteristics of Neusilin® US2 (A) Colloidal silicon dioxide (B) Micronized silicon dioxide (C) grades after loading  0% oil diluted in alcohol and drying at 50°C overnight. Neusilin® showed excellent flow properties and did not show any browning or charring when compared to Colloidal silicon dioxide and Micronized silicon dioxide grades. (The electrostatic charges are generated with Colloidal silicon dioxide and Micronized silicon dioxide grades).

Neusilin® US2, Colloidal silicon dioxide, and Micronized silicon dioxide did adsorb 30% boiled linseed oil diluted with ethanol.

However, compared to Neusilin® US2, both Colloidal silicon dioxide and Micronized silicon dioxide grades were very difficult to handle due to their low bulk density. The blending of linseed oil with both Colloidal silicon dioxide and Micronized silicon dioxide grades resulted in generation of electrostatic charges leading to poor flow characteristics and uneven mixing. 

The most distinct characteristic was that Colloidal silicon dioxide and Micronized silicon dioxide grades on drying at 50°C after oil loading resulted in browning or charring, while Neusilin® US2 remained stable and flowable even at 40% oil load.

Formulation Summary:

Tabletting was carried out for Neusilin® as well as Colloidal silicon dioxide samples and not for Micronized silicon dioxide samples. Tabletting of Micronized silicon dioxide grade was not attempted due to charring. 3g Croscarmellose sodium as a disintegrant and 1g Mg-stearate as lubricant were added to the formulation, and the mixture was sieved through a 30-mesh screen.

Tabletting was carried out in a single punch tabletting machine (Sankyo Piotech) at approximately 5 and 10 kN. Colloidal silicon dioxide-linseed oil tablets showed lower hardness and capping at 10kN compared to Neusilin® linseed oil tablets.

Tablet Characteristics: Tablet weight: 300mg, diameter: 11.3mm

Neusilin® US2 showed superior qualities such as better oil adsorption, hard tablets at low compression force, and easier handling than Colloidal silicon dioxide. Due to the porous nature of US2, the oil-adsorption was very good, and no extrusion was visible on drying, unlike Colloidal silicon dioxide or Micronized silicon dioxide.

Continue reading and see the full Pharmaceutical Technical Newsletter on “Issue 07 – Unveiling Neusilin US2´s Prowness” here:

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MORE ON FUJI

Source: Fuji Chemical Industries technical newsletters Issue 07 – Unveiling Neusilin US2´s Prowness”

Read also the other Technical Newsletter of Fuji Chemical Industries here:

• Issue 04 – Vitamin E Tablets with Fujicalin®
• Issue 05 – F-Melt® oral disintegrating tablets Simvastatin
• Issue 06 – The Cost-Effective Solution For Producing High-Quality Orally Disintegrating Tablets (ODTs) 

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