Chemical Composition and Pharmaceutical Importance of Cellulose and Starch

 

Cellulose

Chemical Composition:

• Structure: Cellulose is a polysaccharide composed of β-D-glucose units linked by β-1,4-glycosidic bonds. The glucose units form long, unbranched chains that are arranged in parallel to each other, forming microfibrils.
• Physical Properties: It is insoluble in water and most organic solvents due to strong intermolecular hydrogen bonding, which creates a crystalline structure.

Pharmaceutical Importance:

• Excipients: Cellulose is widely used as an excipient in pharmaceutical formulations. Microcrystalline cellulose (MCC) is commonly used as a binder and filler in tablets and capsules due to its excellent compressibility and flow properties.
• Controlled Release: Cellulose derivatives, such as hydroxypropyl cellulose (HPC) and hydroxyethyl cellulose (HEC), are used in controlled-release formulations to modify the release rate of active ingredients.
• Disintegration: Cellulose can aid in the disintegration of tablets, ensuring that they break down properly in the digestive system to release the active pharmaceutical ingredient.

Starch

Chemical Composition:

• Structure: Starch is a polysaccharide made up of α-D-glucose units. It exists mainly in two forms: amylose (linear, with α-1,4-glycosidic bonds) and amylopectin (branched, with both α-1,4 and α-1,6-glycosidic bonds).
• Physical Properties: Starch is a granular substance that is soluble in hot water, forming a gel-like consistency upon heating and cooling.

Pharmaceutical Importance:

• Binders and Disintegrants: Starch is commonly used as a binder in tablet formulations, providing cohesion to the tablet mass. It also acts as a disintegrant, helping tablets break apart in the gastrointestinal tract.
• Excipient: It is used in a variety of pharmaceutical products as a filler or diluent, aiding in the formulation and consistency of tablets and capsules.
• Sustained Release: Modified starches, such as pregelatinized starch, are utilized in controlled-release formulations to regulate the release of active ingredients over time.

Both cellulose and starch are integral to pharmaceutical manufacturing, offering versatility in formulation and effectiveness in achieving desired drug delivery outcomes.