Methylcellulose Excipient | Uses, Suppliers, and Specifications
Methylcellulose is a methyl ester of cellulose having a portion of the hydroxyl groups methoxylated. It is available in many different grades depending on the degree of polymerization (in the range 50–1000), and molecular weights (in the range 10 000 – 220 000 Da). Pharmaceutical-grade Methylcellulose is available as a white, powdered or granular material. It is practically odourless and tasteless.
Synonyms and Trade Names: Methylcellulose; E461; BENECEL®; MAPOLOSE®; METHOCEL®; METOLOSE®; TYLOSE®
Uses and Applications: Coating Agent; Suspending Agent; Tablet and Capsule Binder; and Viscosity-Increasing Agent
Methylcellulose is a methyl ester of cellulose of varying chain length and degree of methylation. It is obtained by reacting methyl chloride and alkali cellulose and is one of the most widely used cellulose ethers industrially.
Like other cellulose ethers, Methylcellulose has the polymeric backbone of cellulose, a naturally occurring a linear polymer glucan and is composed of glucose units (> 10 000) linked by β-(1–4)-glycosidic bonds. The number of hydroxyl groups substituted with a methyl ether residue varies between 27-32% while the degree of polymerization is in the range of 50–1000, with molecular weights (number average) in the range 10 000 – 220 000Da. The degree of substitution of methylcellulose is defined as the average number of methoxyl groups attached to each of the anhydroglucose units along the chain.
The degree of substitution has an important impact on the physical properties of Methylcellulose, including properties such as solubility, viscosity in aqueous solution, and glass transition temperature. Pharmaceutical grade Methylcellulose is available as a white, fibrosis powder or granules. It is practically odourless and has no taste. It should be labelled to indicate its viscosity type (for a 2% w/v aqueous solution).
Chemical Structure & Identifiers
|Chemical Name||Cellulose methyl ether|
|CAS Registry Number||[9004-67-5]|
|Molecular weight||10 000 – 2 200 000|
|UNII Code (FDA)||BI55GG2WLI|
Methylcellulose is an approved pharmaceutical excipient. It is listed in all the major pharmacopoeia, including the USP-NF; Ph.Eur, B.P, I.P and JPE. It is also GRAS listed and accepted as a food additive in the USA, Europe and Japan. Methylcellulose is included in the FDA Inactive Ingredients Database (for sublingual tablets; injections; nasal products; ophthalmic products; oral capsules, suspensions, and tablets; topical and vaginal formulations). A specification for methylcellulose is also present in the Food Chemicals Codex (FCC).
|Appearance||White, fibrosis powder or granules|
|pH||pH = 5.0-8.0 for a 1% w/v aqueous suspension.|
|Autoignition temperature||>350 oC (for Methocel A4M)|
|Degree of substitution||1.464 g/ml|
|Glass transition temperature (Tg)||196 oC (for Methocel A4M)|
|Melting point||Starts to brown at 190 – 200 oC; chars at 225-230 oC|
|Refractive index of solution||1.336 (2% aqueous solution)|
|Solubility||Swells and disperses slowly to form a clear to opalescent, viscous, colloidal dispersion in water. Insoluble in ethanol (95%), saturated salt solutions and hot water. Soluble in glacial acetic acid.|
|Surface tension||53-59 mN/m for a 0.05% w/v solution at 250C; 45 – 55mN/m for 0.1% at 20 oC|
|Viscosity (dynamic)||Aqueous solutions (concentrations of 2% w/v) produce viscosities between 5 and 75000 mPas|
|Appearance of solution||n/a||specified||n/a|
|pH||n/a||5.0 -8.0||5.0 -8.0|
|Loss on drying||≤ 5.0%||≤ 5.0%||≤ 5.0%|
|Residue on ignition||≤ 1.5%||≤ 1.5%||≤ 1.5%|
|Heavy metals||≤ 0.001%||≤ 20 ppm||≤ 20 ppm|
|Assay (of methoxyl groups)||27.5 -31.5%||26.0 -33.0%||26.0 -33.0%|
Key: n/a Specification is not listed
*All claims with respect to conformity are subject to our Terms and Conditions. No express or implied warranty is made for specific properties or fitness for any particular application or purpose.
Applications in Pharmaceutical Formulations or Technology
Methylcellulose is in the pharmaceutical industry as a tablet coating agent; emulsifying agent; suspending agent; tablet and capsule disintegrant; tablet binder; viscosity-increasing agent. It is also used as a bulk laxative. The levels used for the different functionalities are shown in the table below:
|Therapeutic (bulk laxative)||5.0 – 30.0|
|Film former in creams, gels and ointments||1.0 – 5.0|
|Ophthalmic preparations||0.5 – 1.0|
|Suspensions||1.0 – 2.0|
|Sustained release tablet matrix formulation (high viscosity grades)||5.0 – 75.0|
|Tablet and capsule binder||1.0 – 5.0|
|Tablet coating agent||0.5 – 5.0|
|Tablet disintegrant||2.0 – 10.0|
Oral dosage forms (liquids and tablets) represent the bulk usage for Methylcellulose. In tablets, low- or medium-viscosity grades are used as binding agents, the methylcellulose being added either as a dry powder or in solution. Highly viscosity grades can also be used in tablets as disintegrating agents. Occasionally, Methylcellulose can be added to tablet formulations to fabricate sustained-release matrices.
Methylcellulose is also widely used as a film former. Tablets can be coated with (either aqueous or organic) solutions of Methylcellulose to obtain conventional coatings. Highly substituted low-viscosity grades of Methylcellulose are suitable for use in taste-masking applications or for modifying the rate of release of drug substances. Methylcellulose has also been used as a sealant during sugar coating applications.
Low-viscosity grades of Methylcellulose have occasionally been utilised to emulsify fixed oils (Olive and Peanut) and Mineral oils, or as suspending materials for orally administered liquid formulations. In these respects, Methylcellulose is used to substitute Sugar-based syrups (e.g Sucrose, Maltitol and Sorbitol) or other suspension systems (e.g Povidone, Copovidone, and Xanthan gum). Methylcellulose is also used to formulate antacids since it delays the settling of suspended solids while increasing the time the drug substance has contact with the lining of the stomach.
In topical formulations, high-viscosity grades of Methylcellulose are used as thickening agents in ointments, creams and gels. In ophthalmic preparations, Methylcelluylose (at 0.5 – 1.0 % w/v concentration) is suitable for use as a vehicle for eye drops. Methylcellulose is also used in injectable formulations.
Finally, Methylcellulose is used therapeutically as a bulk laxative.
Safety and Precautions
Methylcellulose is widely used in the pharmaceutical, cosmetic and food sectors as an excipient, food additive and formulation aid for products administered viral the oral, topical and parenteral routes. It has been used in foods in the United States since the early 1960s, and is now considered a practically nontoxic, non-allergenic, and non-irritant material. No mutagenic activity has also been demonstrated.
Upon oral ingestion, Methylcellulose is not digested or absorbed systemically. It is, however, broken down by normal gut flora. Ingestion of excessive amounts of methylcellulose may temporarily increase gas (flatulence) and bloating. When consumed in large amounts, Methylcellulose may exert a laxative action, which is the reason medium- or high-viscosity grades are used as bulk laxatives.
The WHO has not specified an acceptable daily intake of methylcellulose since the level of use in foods was not considered to be a hazard to health.
Toxicology: LD50 (mouse, IP): 275g/kg
Stability and Storage Conditions
Methylcellulose powder is considered a stable, although slightly hygroscopic excipient. The assigned shelf life is 24-36 months. The bulk excipient should be stored in a tightly-closed container in a cool, dry place.
Methylcellulose solutions are stable to acids and alkalis at pH ranges of 3 – 11. At pH levels <3, acid-catalysed hydrolysis of the glucose-glucose bonds can occur, which reduces the viscosity of the solution. Methylcellulose solutions are also liable to microbial spoilage. Antimicrobial preservatives should therefore be added. Solutions are, however, stable to autoclaving.
When handling the bulk material, workers should observe established SHEQ protocols appropriate to the circumstances and quantity of material handled. Generated dust may irritate the eyes and other mucosae. Therefore, PPE should be worn. Work should be conducted in a well-ventilated area. Refer to the material MSDS for further information.
Sustainability and Environmental Impact
A sustainability assessment for Methylcellulose has not been provided yet.
Manufacturers & Suppliers
Additional Resources (Downloads)
References and Literature Used
 S. Yoshioka, Y. Aso, S. Kojima, The effect of excipients on the molecular mobility of lyophilized formulations, as measured by glass transition temperature and NMR relaxation-based critical mobility temperature, Pharmaceutical Research, 16 (1999) 135-140.
 A.P. Rokhade, N.B. Shelke, S.A. Patil, T.M. Aminabhavi, Novel interpenetrating polymer network microspheres of chitosan and methylcellulose for controlled release of theophylline, Carbohydrate Polymers, 69 (2007) 678-687.
 H. Wikström, W.J. Carroll, L.S. Taylor, Manipulating theophylline monohydrate formation during high-shear wet granulation through improved understanding of the role of pharmaceutical excipients, Pharmaceutical Research, 25 (2008) 923-935.
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