Summary of the Application of "Universal Pharmaceutical Excipient" Silicon Dioxide in the Pharmaceutical Field

Silicon dioxide (commonly known as micronized silica gel in pharmaceutical use, structural formula: mSiO₂·nH₂O) is called the "universal pharmaceutical excipient" in the field of pharmaceutical preparations due to its wide range of raw materials and excellent physicochemical properties (good fluidity, high purity, small particle size, large specific surface area, abundant pores, and good adsorption of surface silanol groups). Its specific applications and related research are as follows:

2.1 Core Application Efficacies and Examples

2.1.1 Glidant

• Mechanism of Action: Small-particle-size silicon dioxide is required to fill the gaps between drug particles, reduce the interaction between particles, and improve the fluidity of granules or powders. It is especially suitable for granulation of oil-based and extract-based drugs to enhance the compressibility of granules.
• Research Example: Wu Yi et al. prepared stemonidine orally disintegrating tablets by direct powder compression method, using 2% silicon dioxide as a glidant. The prepared tablets had a smooth surface and good taste, and the increase in its dosage could accelerate the disintegration rate of the tablets.

2.1.2 Anti-adherent

• Application Scenarios: First, it is used in gel plasters, endowing them with advantages such as large drug-loading capacity, good transdermal effect, excellent skin compatibility, and no irritation, making them a new direction in transdermal drug delivery systems. Second, it prevents materials from adhering to punch heads during tableting, facilitating tablet ejection and preventing tablet splitting to ensure smooth tableting.
• Research Example: Wang Jian et al. found through tests that when the mass fraction of silicon dioxide increased from 1% to 5%, the elastic modulus (G') and viscous modulus (G'') of the gel plaster matrix increased by 99% and 130% respectively, providing a reference for formulation screening.
• Concept Differentiation: In pharmaceutics, "lubricant" is a general term for glidants, anti-adherents, and (narrow-sense) lubricants. Silicon dioxide is customarily classified as a lubricant due to its anti-adhesive or gliding effects, but no excipient can have all three functions simultaneously.

2.1.3 Adsorbent

• Effect: Adsorbs moisture to improve drug properties, enhance the uniformity and fluidity of drug components, and solve the formulation problems of insoluble drugs and Chinese medicine extracts (which are moist and hygroscopic).
• Application Methods:
  • Mix oily/high-moisture main drugs with micronized silica gel to adsorb moisture into dry-wet powders, which can be directly compressed or granulated for tableting as needed;
  • Dissolve insoluble drugs in solvents and adsorb them with micronized silica gel;
  • Direct dry adsorption and mixing, and gradual addition is recommended.
• Research Example: Wang Wenbao et al. used silicon dioxide as an adsorption material to prepare cantharidin liquid-solid compressed tablets, which met the pharmacopoeia standards. The in vitro dissolution rate reached nearly 100% within 120 minutes, solving the problem of low bioavailability of traditional drugs.

2.1.4 Antistatic Agent

• Performance: Eliminates electrostatic adsorption of powders and reduces electrostatic charge and surface resistivity.
• Research Example: Cui Xinmeng et al. used PVC powder as a model drug; after adding 0.8% silicon dioxide, the electrostatic adsorption phenomenon of powders during fluidized bed preparation of micro-particles disappeared, and electrostatic-related indicators decreased significantly.

2.1.5 Grinding Aid

• Mechanism: Promotes the crushing and refinement of raw drug materials, forms co-ground products with high porosity, facilitates rapid water penetration, enhances the disintegration effect of dispersible tablets, improves the water absorption capacity of drugs, and shortens the disintegration time.
• Research Example: Han Xue et al. showed through tests that after modifying curcuma extract with silicon dioxide, the water absorption capacity of curcuma lipid-lowering dispersible tablets was enhanced and the disintegration time was shortened; moreover, co-grinding of silicon dioxide and raw drug materials could strengthen the disintegration effect.

2.1.6 Sustained-Release Preparation Aids

• Value: Regulates drug release, maintains blood drug concentration in the body, improves bioavailability, and can also affect the rate of drug lipolysis and absorption.
• Research Examples:
  • Zhang Hongmei et al. screened the formulation of lovastatin sustained-release tablets; when the dosage of silicon dioxide was 0.2%, the drug release was slow, and the blood drug concentration could be maintained for a long time;
  • Huan Di et al. found that silicon dioxide could increase the drug lipolysis rate of solid self-microemulsifying drug delivery systems (S-SMEDDS), promote absorption, and delay in vitro release, and its influence was related to the dosage.

2.2 Other Extended Applications

2.2.1 Application of Modified Products

Modified products of silicon dioxide are divided into two categories: self-structure modification and blending modification:

• Self-Structure Modification: Mesoporous silica nanoparticles are prepared, which have customized pore structures and ultra-high surface activity. They can be used as drug delivery carriers for therapeutic agents and have obvious advantages in drug packaging and transportation.
• Blending Modification: Microcrystalline cellulose and silicon dioxide are mixed in an appropriate ratio and spray-dried to prepare silicified microcrystalline cellulose, which has good fluidity, compressibility, moisture resistance, and high disintegration. It can be used as a functional diluent for direct tableting, solving the problem of uneven distribution of active ingredients in tablets, and is suitable for the needs of tablet cores, orally disintegrating tablets, dispersible tablets and other preparations.

2.3 Data Source

The summary content is referenced from Research Progress on the Application of Silicon Dioxide as a Pharmaceutical Excipient in Pharmaceutical Preparations (by Men Jing, Jia Wei, Wang Wei, An Min), organized by Xiaoyu from the Powder Industry Circle.

(Note: Part of the content in this document may be AI-generated)