Purified water: It refers to bottled water produced by distillation, deionization, reverse osmosis, etc., which meets the definition of pure water in the latest version of the United States Pharmacopeia.
HPMC: It is an important species of non-ionic cellulose mixed ether. It is odorless, tasteless and non-toxic, and its finished product is white powder or loose fibrous, with particle size passing 80 mesh sieve. It does not react with heavy metals. HPMC is actually a kind of methyl cellulose modified by methane oxide (methyl oxypropylene ring), so it has the similar characteristics of methyl cellulose which is soluble in cold water and insoluble in hot water, and its solubility in organic solvents is better than water solubility, it is soluble in anhydrous methanol and ethanol, and also soluble in chlorinated hydrocarbons such as dichloromethane, trichloromethane and trimethylene oxide. It is soluble in anhydrous methanol and ethanol, but also soluble in chlorinated hydrocarbons such as methylene chloride, trichloroethane and organic solvents such as acetone, isopropanol and diacetone alcohol.
Gelling Agent: Gel agent refers to the drug and suitable excipients made of homogeneous, suspension or emulsion type of latex thick liquid or semi-solid preparation. Gel agent has single-phase dispersion system and two-phase dispersion system, is a two-phase dispersion system of the gel agent is small molecules of inorganic drug colloidal particles in the liquid in a reticular structure, with thixotropy, also known as mixed-suspension gel agent, such as aluminum hydroxide gel. Local application of the gel agent is a single dispersion system, and is divided into aqueous gel agent and oil-based gel agent.
