Methylcellulose

Category

Coating Agents; Emulsifying Agents; Suspending Agents; Tablet and Capsule Disintegrant; Tablet Binder; Viscosity-increasing Agents

Grade

Pharmceutical Excipients

Description

Methylcellulose occurs as a white, fibrous powder or granules. It is practically odorless and tasteless. It should be labeled to indicate its viscosity type (viscosity of a 1 in 50 solution).

UNII

NA

Chemical Name

Cellulose methyl ether

CAS Number

9004-67-5

Synonyms

Benecel; Cellacol; Culminal MC; E461; Mapolose; Methocel; methylcellulosum; Metolose; Tylose; Viscol

Administration route

Sublingual; IM; intrasynovial; nasal; ophthalmic; oral ; topical and vaginal

Dosage Form

Sublingual tablets; IM injections; intrasynovial injections; nasal preparations; ophthalmic preparations; oral capsules, oral suspensions, and oral tablets; topical and vaginal preparations

Stability and Storage Conditions

Methylcellulose powder is stable, although slightly hygroscopic. The bulk material should be stored in an airtight container in a cool, dry place. Solutions of methylcellulose are stable to alkalis and dilute acids at pH 3-11, at room temperature. At pH less than 3, acid-catalyzed hydrolysis of the glucose-glucose linkages occurs and the viscosity of methylcellulose solutions is reduced.On heating, solution viscosity is reduced until gel formation occurs at approximately 50℃. Methylcellulose solutions are liable to microbial spoilage and antimicrobial preservatives should therefore be used. Solutions may also be sterilized by autoclaving, although this process can decrease the viscosity of a solution.The change in viscosity after autoclaving is related to solution pH. Solutions at pH less than 4 had viscosities reduced by more than 20% subsequent to autoclaving.

Source and Preparation

Methylcellulose is prepared from wood pulp (cellulose) by treatment with alkali followed by methylation of the alkali cellulose with methyl chloride. The product is then purified and ground to powder form.

Applications

Methylcellulose is widely used in oral and topical pharmaceutical formulations. In tablet formulations, low- or medium-viscosity grades of methylcellulose are used as binding agents, the methylcellulose being added either as a dry powder or in solution.Highviscosity grades of methylcellulose may also be incorporated in tablet formulations as a disintegrant.

Safety

Methylcellulose is widely used in a variety of oral and topical pharmaceutical formulations. It is also extensively used in cosmetics and food products, and is generally regarded as a nontoxic, nonallergenic, and nonirritant material. Following oral consumption, methylcellulose is not digested or absorbed and is therefore a noncaloric material. Ingestion of excessive amounts of methylcellulose may temporarily increase flatulence and gastrointestinal distension.In the normal individual, oral consumption of large amounts of methylcellulose has a laxative action and medium- or high-viscosity grades are therefore used as bulk laxatives. Esophageal obstruction may occur if methylcellulose is swallowed with an insufficient quantity of liquid. Consumption of large quantities of methylcellulose may additionally interfere with the normal absorption of some minerals. However, this and the other adverse effects discussed above relate mainly to the use of methylcellulose as a bulk laxative and are not significant factors when methylcellulose is used as an excipient in oral preparations. Methylcellulose is not commonly used in parenteral products, although it has been used in intra-articular and intramuscular injections. Studies in rats have suggested that parenterally administered methylcellulose may cause glomerulonephritis and hypertension.Methylcellulose is considered to be toxic by the intraperitoneal route of administration. 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. LD50 (mouse, IP): 275 g/kg

Incompatibilities

Methylcellulose is incompatible with aminacrine hydrochloride; chlorocresol; mercuric chloride; phenol; resorcinol; tannic acid; silver nitrate; cetylpyridinium chloride; p-hydroxybenzoic acid; paminobenzoic acid; methylparaben; propylparaben; and butylparaben.