Hydroxypropyl methylcellulose

Hydroxypropyl methylcellulose (HPMC) or hypromellose refers to soluble methylcellulose ethers. HPMC is used as a thickening agent, binder, film former, and hydrophilic matrix material. HPMC polymers for fabricating hydrophilic matrix systems are available in various viscosity grades ranging from 4000–100,000 mPa s. HPMC is a popular matrix material in oral controlled delivery systems and HPMC matrices show sustained release pattern by two mechanisms, i.e., diffusion and erosion of the gel layer. The viscosity of the polymer affects the diffusion pathway. HPMC can be employed as a matrix for controlling the release of both hydrophilic and hydrophobic drugs. It is being used in buccal adhesive tablets of pentazocine, gastroretentive systems, and colon delivery systems (Al-Tabakha, 2010; Caraballo, 2010).