What is Microcrystalline Cellulose, and How is it Used in Pharmaceuticals?

Microcrystalline cellulose (MCC) is a free-flowing powdery substance extracted as a pulp from fibrous plant material called refined wood pulp. Chemically, it is an insert substance used as a texturizer, extender, emulsifier, and binder in the pharmaceutical industry and a bulking agent in food production. Its vital use is in the making of vitamin supplements and tablets. We will focus more on how MCC is helpful in the pharmaceutical industry.

What is Microcrystalline Cellulose?

● Wood is the most common source of pharmaceutical MCC, in which cellulose chains are closely packed in layered form and are held together by a cross-linking polymer and strong hydrogen bonds. Its crystalline structure is due to its microfibre having a high degree of three-dimensional internal bonding. During compression, MCC plastically deforms, and therefore, interparticle bonding increases. The plasticity of the MCC is the main reason for its exceptional binding property.

● MCC physical properties:

Melting point	76-78 °C(Solv: acetone (67-64-1); chloroform (67-66-3))
Density	1.5 g/cm3 (20℃)
Refractive index	n20/D 1.504
Flash point	164 °C
Storage temp.	room temp
Solubility	Practically insoluble in water, in acetone, in anhydrous ethanol, in toluene, in dilute acids, and a 50 g/L solution of sodium hydroxide
Form	powder
Color	White or almost white
PH	5-7.5 (100g/l, H2O, 20℃)(slurry)
Odor	Odorless
Water Solubility	insoluble
Merck	14,1965
Exposure limits	ACGIH: TWA 10 mg/m3 OSHA: TWA 15 mg/m3; TWA 5 mg/m3 NIOSH: TWA 10 mg/m3; TWA 5 mg/m3; TWA 1 mg/m3
Dielectric constant	3.2（Ambient）
Stability	Stable. Combustible. Incompatible with strong oxidizing agents.

● MCC is obtained from wood pulp and purified cotton linters. However, it can also be acquired from alternate sources like sugarcane residue. The cellulose component is subjected to acid hydrolysis using 2 M hydrochloric acid at 105°C for 15 minutes, and this process releases crystallites, which is the essential binding factor.

Microcrystalline Cellulose Manufacturing Process

The manufacturing process involves several steps. MCC is obtained from wood pulp by contacting an alkali hydrolysis agent at a temperature ranging from 25’ to 70 c. This depolymerizes the cellulose material. The alkaline pulp is then washed to remove the access hydrolysis agent. Then, the washed alkali hydrolyzed pulp is contacted with an acid hydrolysis agent at about 80° C. Microcrystalline cellulose (MCC) is produced through acid hydrolysis of purified wood pulp or cotton. First, the cellulose is treated with an alkali solution, then washed and exposed to concentrated acid at 25-75% by weight. This releases crystalline cellulose fragments. These crystallites are mechanically dispersed to generate MCC powder, which is washed, filtered, dried at 57°-60°C, and milled to the desired particle size. The multi-step manufacturing process results in an MCC with high surface area and moisture absorption abilities, making it useful as a binder and disintegrant.

Microcrystalline Cellulose as a Pharmaceutical Binder

MCC is mainly used as a binder in the pharmaceutical industry due to its outstanding dry-binding properties, enabling it to function effectively in direct compression processes. As a binder, MCC is a crucial component in tablet formulation wet and natural compression processes. Critical aspects of MCC as a pharmaceutical binder include :

● Functionality: As a binder, MCC can deform plastically under compression.

● Critical Material Attributes: Excipients’ variability and impact on drug product performance must be thoroughly understood. MCC’s potential CMAs are listed in the literature, which can help guide its use in pharmaceutical formulations

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● Direct Compression: MCC is commonly used in dry blend and dry granulation processes involving direct compression.

● Tabletability: MCC’s physicochemical properties play a significant role in tablet-ability, and understanding these properties is essential for optimizing tablet formulations

How is Microcrystalline Cellulose Used in Pharmaceuticals?

MCC is a common ingredient nowadays in the pharmaceutical industry. It is used as a strong binder, tablet disintegrant, absorbent, filler, lubricant, and anti-adherent. Microcrystalline cellulose has versatile compressibility properties, making it highly useful in solid pharmaceutical dosage forms like tablets. It allows the formation of hard, stable tablets that still rapidly disintegrate for quick drug release.

Microcrystalline cellulose is essentially refined cellulose that meets the strict quality standards outlined in the United States Pharmacopeia (USP) monograph. This ensures it has the properties needed for pharmaceutical applications.

Beyond pharmaceuticals, microcrystalline cellulose is also commonly used as an additive in many processed foods. It serves various functions in food products, including anti-caking, stabilization, texture modification, and suspension of ingredients. However, the microcrystalline cellulose used in foods may differ from pharmaceutical grades in properties like particle size distribution.

Microcrystalline cellulose is the most commonly used spheronizing aid in a formulation undergoing extrusion spheronization. In addition to pharmaceuticals and foods, microcrystalline cellulose has a wide range of functions in cosmetic products for hair, skin, and makeup. In cosmetics, it is an abrasive for gentle exfoliation, an absorbent, anti-caking agent, a viscosity enhancer, a bulking agent, an emulsion stabilizer, and a texturizer. Microcrystalline cellulose contributes to many cosmetic formulations’ look, feel, spreadability, and stability by influencing properties like texture, absorption, and moisture retention. Its versatility allows it to be incorporated into diverse cosmetic products, including creams, lotions, makeup, cleansers, and hair care items. Formulators can leverage the unique features of microcrystalline cellulose to achieve the desired sensory and visual effects in their cosmetic preparations.

Advantages of Using Microcrystalline Cellulose

● Its strong binding performance makes it one of the most commonly used fillers and binders.
● It has no taste or flavor and is chemically pure; hence, it can be used in pharmaceutical and food products and is generally considered safe (GRAS) by the FDA.
● MCC has more remarkable flowability, which benefits the smooth movement of formulations during manufacturing. This makes it versatile and can be used in various capsules and tablets.

Conclusion

The MCC is widely available and is cost-effective. Its manufacturing process does not include complications, and the finished product is chemically pure, odorless, and tasteless, making it safe for human consumption, animals, and the environment. It’s powdery and has crystalline properties, making it suitable as a binding agent in the pharma industry. The global microcrystalline cellulose market is projected to grow significantly, indicating its increasing importance and usage in various industries.