Methylcellulose INDEX

Substituted Cellulose Ethers. Since their introduction for ophthalmic use, MC and other substituted cellulose ethers such as hydroxyethylcellulose, hydroxypropylcel-lulose, hydroxypropyl methylcellulose (HPMC), and carboxymethylcellulose (CMC) have been used in artificial tear formulations.These colloids dissolve in water to produce colorless solutions of varying viscosity. They have the proper optical clarity, a refractive index similar to the cornea, and are nearly inert chemically. Their relative lack of toxicity, their viscous properties, and their beneficial effects on tear film stability have made cellulose ethers useful components of artificial tear preparations. Historically, the most frequently used representative of this group was MC. 

Methylcellulose is a vehicle used in eye-drops and contact lens solutions (SEDA-1, 369). It is non-irritant and has a good refractive index. A 1% solution is well retained in the conjunctival sac. Corneal cultures have been stimulated by methylcellulose, resulting in increased growth of cells (2) tear-film break-up time was increased four-fold with 2% methylcellulose. Hydroxypropyl methylcellulose is also used as artificial tears for people with dry eyes (3). 

Methylcellulose (MC) 4,000 inPa s 0.5-1.25 % or 5-12.5 mg/mL Methylcellulose is a non-ionic cellulose polymer. The high viscosity types of methylcellulose are employed, because at low concentration solutions are viscous enough and the refiactive index is only slightly changed... 

Methylcellulose, carboxymethyl cellulose, polyvinyl alcohol, sodium polyacrylic, and polyacrylamide copolymer are also used for thickening agents. The qualities of methylcellulose and carboxymethyl cellulose are checked measuring the viscosity of water solution of 2-5%. For polyvinyl alcohol, viscosity (4% at 20°C), saponification number, and polymerization degree are indexes of the quahty. 

Methylcellulose is a useful drug vehicle which is not irritating and has a good refractive index for use on the eye, while a 1% solution is well retained in the conjunctival... 

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