An initial letter identifies the type of cellulose ether. The number that follows identifies the viscosity in millipascal-seconds mPa. In designating viscosity, the letter "C" is frequently used to represent and the letter "M" is used to represent 1, In the USP this is referred to as the labeled viscosity. It is also given on the DuPont sales specification as the nominal viscosity.
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Types of meto lose by Shin-Etsu Chemical 20 PowerPoint Presentation: General information on major factors : Drug solubility is one of the most influential factors for designing a drug release pattern. Highly water- soluble drugs require higher amounts of HPMC in the tablet.
Preparation method also affects the dissolution profile due to the difference of HPMC particle distribution in the tablet. Direct compression methods can avoid such processing factors. After administration , hydrophilic matrix tablets made with HPMC hydrate to form a gel layer, which regulates the drug release pattern.
The most important aspect of this matrix system is the homogeneity of HPMC particle distribution in the tablet. The selection of HPMC grades affects the initial wetting, swelling, hydration and gel strength. PowerPoint Presentation: In the first stage , usually within 30 to 60 minutes after administration, before the completion of the gel layer, the polymer particles on the tablet surface become partially hydrated. Sometimes surface erosion or excess dissolution can be observed in tins period.
In the second stage , the gel layer is completed, and a steady dissolution of the active ingredient occurs. The matrix system has several advantages as follows, 1. It is very simple and easy to establish a formulation. The tablet is completely dissolved and thus achieves good bioavailability. It is easy to control the dissolution profile by selecting a specific grade. The matrix system is an economical method for obtaining controlled release products.
Since it is nonionic , hypromellose will not complex with metallic salts or ionic organics to form insoluble precipitates. Incompatibilities 27 PowerPoint Presentation: Applications in Pharmaceutical Formulation or Technology Hypromellose is widely used in oral, ophthalmic and topical pharmaceutical formulations.
In oral products, hypromellose is primarily used as a tablet binder, in film-coating , and as a matrix for use in extended-release tablet formulations. Lower-viscosity grades are used in aqueous film-coating solutions , while higher-viscosity grades are used with organic solvents.
Examples of film-coating materials that are commercially available include AnyCoat C, Spectracel , and Pharmacoat. Hypromellose is also used as a suspending and thickening agent in topical formulations.
Compared with methylcellulose, hypromellose produces aqueous solutions of greater clarity, with fewer undispersed fibers present, and is therefore preferred in formulations for ophthalmic use. Hypromellose at concentrations between 0.
As a protective colloid, it can prevent droplets and particles from coalescing or agglomerating, thus inhibiting the formation of sediments. In addition, hypromellose is used in the manufacture of capsules , as an adhesive in plastic bandages, and as a wetting agent for hard contact lenses. It is also widely used in cosmetics and food products. Several materials have been examined as a substitute for the gelatin in two-piece hard capsules. Hydroxypropylmethyl cellulose HPMC has become a successful alternative material for two-piece capsules and is actually on the market in the world.
COM 2. COM 4. Hand book of pharmaceutical excipient 5 th edition 5. Hogan JE. Hydroxypropylmethylcellulose sustained release technology. Drug Dev Ind Pharm ; —
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