HPMC is formed by the hydroxypropyl and methyl substitution of cellulose, which alters its physical and chemical properties. Its chemical structure allows it to hold water, providing excellent film-forming and thickening capabilities. The degree of substitution can vary, allowing for different forms of HPMC, which can have a significant impact on its solubility and viscosity in aqueous solutions. Typically, HPMC is white to off-white powder and is soluble in water, forming a clear, viscous gel upon hydration.
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In the pharmaceutical industry, HPMC serves multiple roles. It is commonly used as a binder in tablet formulations, enhancing the mechanical strength and disintegration properties of tablets. HPMC is also utilized in drug delivery systems due to its ability to form matrices that control the release of active pharmaceutical ingredients. This controlled release not only improves bioavailability but also extends the duration of drug action, minimizing the need for frequent dosing. Furthermore, HPMC is employed in ocular solutions, where it aids in providing lubrication and enhancing the comfort of contact lenses.