Cellulose hydroxypropylmethylcellulose

Hydroxypropylmethylcellulose Methylcellulose Hydroxyethyl cellulose Hydroxypropylmethylcellulose -I- mannitol, glucose, or glycerol PMMA Avoids adsorption of fluorescently labeled oligosaccharides to capillary surfaces Improves separation of PCR products by low-viscosity sieving matrix... 

Health and Safety Factors. No adverse toxicological or environmental factors are reported for cellulose ethers in general (33,60-73). Some are even approved as direct food additives, including purified carboxymethylcellulose, methyl-cellulose, hydroxypropylmethylcellulose, and hydroxypropylcellulose. 

Fluidized aqueous suspensions of 15% by weight or more of hydroxyethyl-cellulose, hydrophobically modified cellulose ether, hydrophobically modified hydroxyethylcellulose, methylcellulose, hydroxypropylmethylcellulose, and polyethylene oxide are prepared by adding the polymer to a concentrated sodium formate solution containing xanthan gum as a stabilizer [278]. The xanthan gum is dissolved in water before sodium formate is added. Then the polymer is added to the solution to form a fluid suspension of the polymers. The polymer suspension can serve as an aqueous concentrate for further use. 

Ketoprofen (SIMS), hydroxypropylmethylcellulose E5 (HPMC, t =2%, 5mPas, Dow Chemical), glyceryl monostearate (Precirol, Gattefosse), Eudragit E 30 D (Rhom Pharma), Polyethylene glycol 400 (PEG 400, Merck) and cellulose acetate phthalate (CAP, Ambrochim) were used directly without any prior purification. 

The use of cellulose ethers in producing matrix-type sustained release tablets is well documented [7]. Hydrophilic matrices of ketoprofen with hydroxypropylmethylcellulose (KET-R)... 

These stabilizers are added to the formulation in order to stabilize the emulsion formed during particle preparation. These stabilizers, however, can also influence the properties of the particles formed. The type and concentration of the stabilizer selected may affect the particle size. Being present at the boundary layer between the water phase and the organic phase during particle formation, the stabilizer can also be incorporated on the particle surface, modifying particle properties such as particle zeta potential and mucoadhesion (203). Other polymers have also been evaluated as stabilizers in earlier studies such as cellulosic derivatives methylcellu-lose (MC), hydroxyethylcellulose ( ), hydroxypropylcellulose (HPC), and hydroxypropylmethylcellulose (HPMC), as well as gelatin type A and B, carbomer and poloxamer (203). 

Methylcellulose is made by reaction of alkali cellulose with methyl chloride until the DS reaches 1.1—2.2. Hydroxypropylmethylcellulose [9004-65-3], the most common of this family of products, is made by using propylene oxide in addition to methyl chloride in the reaction MS values of the hydroxypropyl group in commercial products are 0.02—0.3. Use of 1,2-butylene oxide in the alkylation reaction mixture gives hydroxybutylmethylcellulose [9041-56-9, 37228-15-2] (MS 0.04—0.11). Hydroxyethylmethylcellulose [903242-2] is made with ethylene oxide in the reaction mixture. 

Other thickeners used include derivatives of cellulose such as methylcellulose, hydroxypropylmethylcellulose, and cellulose gum natural gums such as tragacanth and xanthan (see Cellulose ethers Gums) the carboxyvinyl polymers and the poly(vinyl alcohol)s. The magnesium aluminum silicates, glycol stearates, and fatty alcohols in shampoos also can affect viscosity. 

The salt form of the polymer may also play a role in determining the performance of the formulation. Kane et al. [32] found that cellulose acetate phthalate was more effective than cellulose acetate trimellitate in controlling the dissolution of sulfothiazole-sodium tablets with cellulose acetate. The enteric properties of hydroxypropylmethylcellulose phthalate (HPMCP) were found to depend on the solubility of the drug that was coated. 

Methylcellulose solutions generally form gels at higher temperatures. The gelation temperature is increased when hydroxyethyl or hydroxypropyl groups are introduced into the methylcellulose (cf. Section 9.6.2). Hy-droxyethylmethylcellulose and hydroxypropylmethylcellulose are prepared industrially by the reaction of alkali cellulose first with ethylene oxide or propylene oxide and then with methyl chloride. Similarly, hydroxyethyl-ethylcellulose is prepared by consecutive ethylene oxide and ethyl chloride treatments. Cellulose ethers with both methyl and ethyl groups have also been manufactured. 

The reaction of alkali cellulose with a mixture of methyl chloride and propylene oxide can produce hydroxypropylmethylcellulose (HPMC). 

Lindberg NO. Water vapour transmission through free films of hydroxypropyl cellulose. Acta Pharm Suec 1971 8 541-548. Banker G, Peck G, Williams E, et al. Evaluation of hydroxypro-pylcellulose and hydroxypropylmethylcellulose as aqueous based film coatings. Drug Dev Ind Pharm 1981 7 693-716. 

Additives used for decreasing the EOF and/or protein adsorption are often cellulose derivatives [e.g., hydroxypropylmethylcellulose (HPMC)]. The cellulose adsorbs to the capillary surface. Hereby, the viscosity will increase at the capillary surface (more than in bulk solution), causing a reduction in EOF as well as a decrease in protein adsorption to the capillary wall. The tendency for protein precipitation will also decrease by addition of cellulose derivatives. 

This class of cellulose derivatives includes hydroxypropylmethylcellulose or HPMC, hydroxyethylcellulose (58), methylcellulose, HPC, and ethylcellulose. As mentioned earlier, most cellulose-based polymers except for PVP, have lower surface tension values in the range of 40-50 mN/m, thus similar adhesive and film-forming qualities will be seen. 

The core may be a water-soluble polymer, an inert salt or, as in the case of metoprolol fumarate, the drug itself, whose saturated solution has an osmotic pressure of 32.5 atm. The osmotic tablet of nifedipine is described in detail in Fig. 8.38, which shows the semipermeable cellulose acetate coating, the swellable hydrogel layer of polyoxyethylene glycol and hydroxypropylmethylcellulose (HPMC) and the dmg chamber containing nifedipine in HPMC and PEG. 

Polymeric gums are also important compounds for building viscosity in shampoos and conditioners. They are easily dispersed in water at common use levels of 0.5 to 1.5%. The most commonly used cellulose polymer is hydroxyethycellu-lose, which is compatible with anionic and cationic surfactants and stable over a wide pH range [24], Other cellulose polymers in use include methylcellulose and hydroxypropylmethylcellulose. 

Methylethylcellulose (MEC) Methylhydroxyethylcellulose (MHEC) Hydroxypropylmethylcellulose (HPMQ Hydroxybutylmethylcellulose (HBMC) Ethylhydroxyethylcellulose (EHEQ Sodium carboxymethylhydroxyethyl-cellulose (NaCMHEC, CMHEQ Carboxymethylethylcellulose (CMEC)... 

Fig. 3. Variation of the glass transition temperature of ethylceUulose/hydroxypropylmethylcellulose blends with blend composition and diethyl phthalate concentration (A) 20/80, (B) 40/60, (Q 60/40, and (D) 80/20 w/w ethylcellulose/hydroxypropylmethylcellulose. ( ) T, of hydroxypropylmethyl-cellulose-rich phase (O) Tg of ethylcellulose-rich phase. Full lines represent the behavior of the individual polymers [65]...

HPMC hydroxypropylmethylcellulose CMC carboxymethyl-cellulose HEC hydroxyethylcellulose HPC hydroxypropyl-cellulose EC ethylcellulose PVP polyvinylpyrrolidone PVA poly(vinyl alcohol) poly(HEMA) poly(hydroxyethyl methacrylate). 

Starch derivatives Water-soluble cellulose derivatives Carboxymethylcellulose, sodium salt Hydioxyethylcellulose Hydroxypropylcellulose Hydroxypropylmethylcellulose Methylcellulose... 

Properties. Methylcellulose [9004-67-5] (MC) and its alkylene oxide derivatives hydroxypropylmethylcellulose [9004-65-3] (HPMC), hydroxyethylmethyl-cellulose [9032-42-2] (HEMC), and hydroxybutylmethylcellulose [9041-56-9] (HBMC) are nonionic, surface-active, water-soluble polymers. Each type of derivative is available in a range of methyl and hydroxyalkyl substitutions. The extent and imiformity of the methyl substitution and the specific type of hydroxyalkyl substituent affect the solubility, surface activity, thermal gelation, and other properties of the poljuners in solution. 

---