Silicified Microcrystalline Cellulose Excipient | Uses, Suppliers, and Specifications
Silicified Microcrystalline Cellulose (SMCC) is a co-processed functional excipient consisting of two excipients: microcrystalline cellulose (98%), and colloidal silicon dioxide (2%). The two constituent materials are intimately and physically combined using a proprietary process to create a physically stable, high performance tableting excipient.
Synonyms and Trade Names: Silicified Microcrystalline Cellulose; SMCC; Microcrystalline Cellulose, Silicified; Comprecel® SMCC; PROSOLV® SMCC; Avicel® SMCC
Uses and Applications: Direct Compression Filler-Diluent, Dry Binder, and Formulation Performance Enhancer
Silicified Microcrystalline Cellulose (SMCC) is a co-processed pharmaceutical excipient consisting of two functional excipients: Microcrystalline cellulose, and Colloidal silicon dioxide. The two constituent materials are non-covalently bound but highly stable.
SMCC was developed to address the challenges formulators faced with standard Microcrystalline cellulose during direct compression operations, namely, low bulk density, poor flowability, sub-optimal compactibility, and sensitivity to lubricants (mainly, Magnesium stearate), especially when used in direct compression formulations.
The secret factor to the uniqueness of SMCC is how it is made. Basically, Colloidal silicon dioxide is added to an aqueous slurry of Microcrystalline cellulose. In this hydrated state, the silica is able to completely and uniformly disperse and envelop the particles of Microcrystalline cellulose. Subsequent spray drying of the mixture allows the silica particles to intimately bind to the surface of microcrystalline cellulose particles.
Silicification imparts superior functionality to SMCC, namely increase in specific surface area, improvement of flowability, lowering of a formulation’s cohesiveness, and elimination of lubricant and strain-rate sensitivity (owing to improvement of brittle fracturing of particles). From a tableting perspective, these changes make formulations that incorporate SMCC more manageable even when they contain problematic active ingredients (for example, micronised, poorly compactible, soft, sticky, or low dose).
Since the introduction of SMCC over two decades ago, formulators and manufacturers now have access to a superstar, multifunctional excipient that offers many benefits, without a significant increase in formulation costs. And the good thing is that supply is now less constrained with newer manufacturers based in India and China coming on board in recent years.
Chemical Structure & Identifiers
|CAS Registry Number:||[9004-34-61]|
|Molecular Weight:||Approx. 36 000
where n = approx. 220
|UNII Code (FDA):||OP1R32D61U|
|Chemical Name||Silicon dioxide, chemically synthesised|
|CAS Registration Number||[112945-52-5]|
|UNII Code (FDA)||ETJ7Z6XBU4|
Silicified microcrystalline cellulose is an approved pharmaceutical excipient. Although the material has no monograph, both Colloidal silicon dioxide and Microcrystalline cellulose are listed in separate monographs in the USP-NF; PhEur, J.P, as well as the B.P and I.P. Microcrystalline cellulose is also GRAS listed and included in the US FDA Inactive Ingredients Database. Colloidal silicon dioxide is similarly GRAS listed and included in the FDA Inactive Ingredients Database.
|Physical form||Solid, powder|
|Appearance||White fibrous powder|
|pH value||5.0-7.5 (10% w/v aqueous suspension)|
|Poured Density||Varies between 0.25 and0.50 g/cm3
0.25-0.37 (PROSOLV® SMCC 50 )
0.25-0.37 (PROSOLV® SMCC 90 )
0.38-0.50 (PROSOLV® SMCC HD 90 )
|Tapped Density||0.39-0.41 g/cm3|
|Melting point||Microcrystalline cellulose chars at 260-270oC.|
|Moisture content||Typically not more than 5 % w/w|
|Particle size distribution||20-200 µm depending on grade|
|Specific surface area||110 m2/g|
|Solubility||Slightly soluble in NaOH solution; practically insoluble in water, acetone, ethanol, toluene, and diluted acid|
Applications in Pharmaceutical Formulations or Technology
Silicified MCC exhibits better flowability and reduced cohesiveness compared to non-silicified Microcrystalline cellulose grades. In pharmaceutical products, Silicified microcrystalline cellulose functions as a filler-diluent in direct compression or capsule filling operations. It can also be added to wet granulated powder mixes (extragranularly) to improve the compaction properties of formulations, particularly for those situations when standard Microcrystalline cellulose is not capable of doing the job.
Indeed, this is the very reason Silicified microcrystalline cellulose was developed: to address the loss of compactibility that occurs with microcrystalline cellulose after wet granulation or when exposed to compressive stresses (hornification phenomenon). The typical usage levels range from 10% to as high as 25%, depending on the formulation characteristics and challenges being solved.
Silicified Microcrystalline cellulose (SMCC) exhibits higher compact strength (tensile strength) and therefore requires lower compression forces compared with standard Microcrystalline cellulose grades. In addition, at similar concentrations, SMCC tablets have higher crushing strengths compared with those made from standard Microcrystalline cellulose.
Safety and Precautions
Silicified microcrystalline cellulose is a relatively new material, however, its constituent materials have a long history of safe use as excipients and food additives and present no appreciable concerns for consumer safety. They are no absorbed systemically following oral administration.
However, Silicified microcrystalline cellulose may irritate the eyes and other sensitive mucous membranes. When handling SMCC, observance of work safety precautions appropriate to the circumstances and quantity of material handled are recommended. Gloves, eye protection and a dust mask should be used. Since the handling of Silicified microcrystalline cellulose can generate nuisance dust, the use of a respirator or dust mask is often necessary.
Stability and Storage Conditions
Silicified Microcrystalline cellulose (SMCC) is stable provided it is stored in a well- closed container in a cool, dry place. The typical shelf life is 3 years, and may be extended subject to the usual tests.
Sustainability and Environmental Impact
Silicified Microcrystalline Cellulose (SMCC) is partly sourced from sustainable sources (wood pulp) and unsustainable sources (silicon dioxide). For this reason, SMCC achieved a total score of 78/100 by the Excipients Forum Sustainable Chemistry Score ™.
Manufacturers & Suppliers
Dupont (United States), which markets its Silicified Microcrystalline Cellulose (SMCC) under the AVICEL® SMCC brand name. AVICEL® SMCC is available in three grades, namely Avicel® SMCC 50; Avicel® SMCC 90; and Avicel® SMCC HD 90.
JRS Pharma (Germany), which is the innovator of SMCC, markets it under the PROSOLV® brand name. A total of five grades is available, namely PROSOLV® SMCC 50 LD; PROSOLV® SMCC 50; PROSOLV® SMCC 90; PROSOLV® SMCC HD 90; PROSOLV® SMCC 90 LM.
Mingtai Chemical Company. (Taiwan), which markets its SMCC under the COMPRECEL® SMCC brand name. Four grades are available, namely COMPRECEL® SMCC 50; COMPRECEL® SMCC 90; COMPRECEL® SMCC 90 HD; and COMPRECEL® SMCC 90 LM
Additional Resources (Downloads)
Avicel-Product-Selection-Guide-pharmacentral roquette-pharma-oral-dosage-nutraceuticals-odt-brochure-microcel Vivapur-information-sheet-pharmacentral Emcocel-information-sheet-pharmacentral Avicel-PH-101-specification-pharmacentral
References and Literature Used
 M.J. Tobyn, G.P. McCarthy, J.N. Staniforth, S. Edge, Physicochemical comparison between microcrystalline cellulose and silicified microcrystalline cellulose, International journal of pharmaceutics, 169 (1998) 183-194.
 S. Edge, D.F. Steele, A. Chen, M.J. Tobyn, J.N. Staniforth, The mechanical properties of compacts of microcrystalline cellulose and silicified microcrystalline cellulose, International journal of pharmaceutics, 200 (2000) 67-72.
 Haiyue Zhao, Lijie Zhao, Xiao Lin, Lan Shen,An update on microcrystalline cellulose in direct compression: Functionality, critical material attributes, and co-processed excipients, Carbohydrate Polymers, 278, 2022,118968,https://doi.org/10.1016/j.carbpol.2021.118968.
 Kristensen, T. Schæfer, P. Kleinebudde, Direct pelletization in a rotary processor controlled by torque measurements. II: effects of changes in the content of Microcrystalline Cellulose, AAPS PharmSci, 2 (2000) 45. https://doi.org/10.1208/ps020324. Pubmed | Google Scholar
 Van Veen, G.K. Bolhuis, Y.S. Wu, K. Zuurman, H.W. Frijlink, Compaction mechanism and tablet strength of unlubricated and lubricated (silicified) Microcrystalline Cellulose, European journal of Pharmaceutics and Biopharmaceutics, 59 (2005) 133-138. https://doi.org/10.1016/j.ejpb.2004.05.009. Pubmed | Google Scholar
Buy Secondary Reference Standards Certified to Ph.Eur and USP-NF