Hydroxypropyl cellulose

• BPHydroxypropylcellulose
• JPHydroxypropylcellulose
• Ph. Eur.Hydroxypropylcellulose
• USP–NFHydroxypropyl Cellulose

Cellulose, hydroxypropyl ether; HPC; hyprolose; Klucel; Nisso HPC; oxypropylated cellulose; E463

Cellulose, 2-hydroxypropyl ether · [9004-64-2]

Polymer, mixture or material of variable composition — no single molecular formula applies.

Binder

Typical concentrations: 2–6% · Dosage forms: Solid

Used in oral products as a tablet binder in wet and dry granulation (2–6%), as a film former for tablet coating (about 5% solutions), and as an extended-release matrix former (15–35%). It is also used as a thickener in topical and oral liquids, in hot-melt extrusion, in transdermal films and as a stabiliser for suspensions. Fine-particle grades are used for direct-compression binding.

A white to slightly yellow, odourless and tasteless powder or granules. It is a thermoplastic, non-ionic cellulose ether with a high level of hydroxypropyl substitution, which gives it solubility in both water and polar organic solvents.

Hydroxypropoxy content

≤ 80.5% (USP–NF); molar substitution about 3.5–4

pH

5.0–8.5 (1% w/v aqueous solution)

Solubility

soluble in cold water and in ethanol, methanol, propylene glycol and other polar solvents; insoluble in hot water, from which it precipitates at about 40–45 °C

Viscosity

grades from very low to very high (for example a few mPa·s to several thousand mPa·s in 2% w/v solution)

Moisture content

typically below 5% w/w as packed; moderately hygroscopic

The powder is stable but hygroscopic; store in a well-closed container in a cool, dry place. Aqueous solutions are most stable at about pH 6–8; viscosity may fall through acid hydrolysis at low pH and alkaline oxidation at high pH, and through exposure to UV light. Solutions are susceptible to microbial and enzymatic degradation and should be preserved.

Interacts with substituted phenolic compounds such as methylparaben and propylparaben, which can cause precipitation. High concentrations of dissolved salts or other solutes reduce its solubility and may cause it to salt out. Some anionic polymers can increase the viscosity of its solutions.

Made by reacting alkali cellulose with propylene oxide at elevated temperature and pressure. The product is purified to remove by-products, then dried and milled to the required particle size.

Widely used in oral and topical products and regarded as essentially non-toxic and non-irritant; it is not absorbed from the gastrointestinal tract. Very large oral doses may have a laxative effect.

Observe normal precautions for the quantity handled. Avoid generating dust, which is combustible and may irritate the eyes; eye protection and gloves are recommended.

Accepted as a food additive in Europe (E463). Included in the FDA Inactive Ingredient Database (oral capsules, granules, suspensions and tablets; topical and transdermal preparations) and in non-parenteral medicines licensed in Europe.

Hydroxyethyl cellulose; hydroxypropyl cellulose, low-substituted; hypromellose; methylcellulose.

Its solubility in ethanol makes it useful for non-aqueous granulation of moisture-sensitive drugs and for organic-solvent coating. Films are flexible but somewhat tacky, so it is often combined with other film formers. It should not be confused with low-substituted hydroxypropyl cellulose, which is water-insoluble and used as a disintegrant.