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. Methylcellulose may be added to a tablet formulation to produce sustained-release preparations. Tablet cores may also be spray-coated with either aqueous or organic solutions of highly substituted low-viscosity grades of methylcellulose to mask an unpleasant taste or to modify the release of a drug by controlling the physical nature of the granules. Methylcellulose coats are also used for sealing tablet cores prior to sugar coating. Low-viscosity grades of methylcellulose are used to emulsify olive, peanut, and mineral oils. They are also used as suspending or thickening agents for orally administered liquids, methylcellulose commonly being used in place of sugar-based syrups or other suspension bases. Methylcellulose delays the settling of suspensions and increases the contact time of drugs, such as antacids, in the stomach. High-viscosity grades of methylcellulose are used to thicken topically applied products such as creams and gels. In ophthalmic preparations, a 0.5–1.0% w/v solution of a highly substituted, high-viscosity grade of methylcellulose has been used as a vehicle for eye drops. However, hypromellose-based formulations are now preferred for ophthalmic preparations. Methylcellulose is also used in injectable formulations.