Hypromellose – A traditional pharmaceutical excipient

Hypromellose, also known as hydroxypropyl methylcellulose (HPMC), is a traditional pharmaceutical excipient widely used in the pharmaceutical industry for various purposes. It belongs to the class of cellulose ethers and is derived from cellulose, a natural polymer found in plant cell walls. Hypromellose is synthesized by treating cellulose with propylene oxide and methyl chloride.

Here are some key features and roles of hypromellose as a pharmaceutical excipient:

1. Binder: Hypromellose is often used as a binder in tablet formulations. It helps to bind the active pharmaceutical ingredients (APIs) and other excipients together, ensuring the tablet maintains its shape and integrity during manufacturing and handling.
2. Film Coating Agent: Hypromellose is utilized as a film coating agent to provide a protective and smooth coating to tablets and capsules. This coating can mask unpleasant tastes, improve appearance, protect against moisture, and control the release of the drug.
3. Matrix Former: In sustained-release formulations, hypromellose can be used as a matrix former. It forms a gel-like matrix when in contact with water, controlling the release of the drug over an extended period, thus providing prolonged drug action.
4. Viscosity Modifier: Hypromellose is often employed to adjust the viscosity of liquid formulations such as oral suspensions and topical preparations. It helps to stabilize suspensions, control rheology, and improve pourability and spreadability.
5. Disintegrant: In certain formulations, hypromellose can act as a disintegrant, promoting the rapid breakup of tablets or capsules into smaller particles when exposed to water in the gastrointestinal tract, thereby facilitating drug dissolution and absorption.
6. Emulsifier and Stabilizer: Hypromellose can serve as an emulsifying agent and stabilizer in emulsions and creams, helping to create stable and uniform formulations for topical application.
7. Mucoadhesive: In ocular formulations or nasal sprays, hypromellose can act as a mucoadhesive agent, promoting adhesion to mucosal surfaces and prolonging the contact time of the drug with the target tissue.

Overall, hypromellose is a versatile pharmaceutical excipient valued for its biocompatibility, non-toxicity, and wide range of applications in dosage forms such as tablets, capsules, films, suspensions, and creams. Its properties make it an essential component in the formulation of various pharmaceutical products, contributing to their efficacy, stability, and patient acceptability.