Harnessing the Power of Neusilin® in HPMC Matrix Tablets

OVERVIEW

Hydrophilic matrices, particularly those formulated with hypromellose (HPMC), are essential for controlled drug release in pharmaceutical formulations. While HPMC offers numerous advantages, its propensity to exhibit a burst release effect remains a significant challenge.

While this can be beneficial in certain cases, it often leads to suboptimal therapeutic outcomes and increased adverse effects. To ensure consistent drug delivery and optimize therapeutic efficacy, minimizing initial burst release is crucial in controlled-release formulations. Traditional excipients like microcrystalline cellulose (MCC) have been employed to mitigate this effect, but the pursuit of novel excipients with superior properties for controlled drug release continues.

NEUSILIN®: THE GAME-CHANGER

Neusilin®, an amorphous magnesium aluminometasilicate, has gained prominence as a versatile excipient in pharmaceutical formulations. Its distinctive characteristics, including a high specific surface area and adsorption capacity, make it well-suited for modulating drug release profiles.

A recent study by Bilik et al., featured in this newsletter, elucidated the effectiveness of incorporating Neusilin® into HPMC matrix tablets. The inclusion of Neusilin® significantly reduced the initial burst release of soluble drugs, such as caffeine, providing a more controlled and sustained release profile from matrices with 10-20% of HPMC content.

OPTIMIZATION OF POWDER BLENDS FOR TABLET PRODUCTION

Mixing and Characterization
- All ingredients, as specified in Table 1, were thoroughly mixed using a three-axial homogenizer
  turbula for 10 minutes.
- Prior to tablet preparation, the powder blends were characterized for their flow properties.
Tablet Preparation
- Convex-faced HPMC matrices were directly compressed using an eccentric tablet press to achieve maximum hardness.
Evaluation
- The prepared tablets were subjected to a comprehensive evaluation, including assessments of weight, content uniformity, hardness, friability and dissolution
- Dissolution studies were conducted to assess the rate and extent of drug release from the tablets.

TABLE 1: MATRIX TABLETS COMPOSITION *

*Each sample contains 0.5% of Aerosil® 200 and 2.5% of magnesium stearate for better flowability and compression feasibility. ** HPMC amount always corresponds to 150 minus the numeric value or the sum ofthe numeric values in the sample designation. — *Each sample contains 0.5% of Aerosil® 200 and 2.5% of magnesium stearate for better flowability and compression feasibility. ** HPMC amount always corresponds to 150 minus the numeric value or the sum of the numeric values in the sample designation.

IMPACT OF NEUSILIN®

NEUSILIN® US2 ON TABLET FORMULATION AND MECHANICAL PROPERTIES

Enhanced Tablet Hardness and Compressibility: Neusilin® US2,

when incorporated as a filler, significantly improved the mechanical properties of the tablets. This was manifested by enhanced tablet hardness and excellent compression characteristics.

NEUSILIN® ON THE FORMATION OF HPMC GEL LAYER

Neusilin® matrices formed thicker gel layers than MCC matrices but required less penetration force

due to Neusilin®’s higher adsorption capacity, which allowed for deeper penetration of the dissolution medium
and promoted HPMC swelling. However, individual Neusilin® particles disrupted the gel layer more significantly than MCC alone or Neusilin® / MCC combinations, leading to faster drug release. This is depicted in figure no. 2.