Hydroxypropylmethylcellulose HPMC

Hydroxypropylmethylcellulose HPMC Cold water, GI fluids, methanol/methylene chloride, alcohol/fluorohydrocarbons Excellent film former and readily soluble throughout GIT low-viscosity grades to be preferred, e.g., Methocel HG (Dow)... 

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). 

However, some negative effects of the combination of CyDs and polysaccharide on the rectal drug delivery were reported. Lin et al. [38] demonstrated that the mixture of (3-CyD and hydroxypropylmethylcellulose (HPMC) markedly reduced the in vivo bioavailability of acetaminophen from both aqueous solution and hydrogels. Not only the lower partition coefficient but also the higher hydrophilic property of the (3-CyD complex and the higher viscosity of HPMC hydrogel matrix might be responsible for the decrease in the in vitro permeation rate and depression of in vivo rectal absorption of acetaminophen. 

The polymers are usually applied either from aqueous or from organic solvent. More recently, aqueous dispersions or redispersible powders of the polymers have become available that ensure economical, fast, and environmentally safe processing of the film coatings. In some cases it might be necessary to prevent an interaction between the acidic functional groups and the drug. In these cases a subcoat (e.g., of hydroxypropylmethylcellulose [HPMC]) is recommended. 

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

Daniels, R. Schulz, M.B. Hydroxypropylmethylcellulose (HPMC) as emulsifier for submicron emulsions influence of molecular weight and substitution type on droplet size after high-pressure homogenization. Eur. J. Pharm. Biopharm. 2000, 49, 231-236. 

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. 

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. 

It is normally difficult to produce tablets with ascorbic acid by direct compression, but as is shown in Table 174, they can be produced much more readily using copovidone. When this dry binder is added, the hardness of the tablets increases and the friability decreases much more than after the addition of povidone K 30 or hydroxypropylmethylcellulose (HPMC) which had no effect on the hardness in this formulation. Similar results were shown in Fig. 111 for acetaminophen tablets. 

Fyfe CA, Blazek Al. Investigation of hydrogel formation from hydroxypropylmethylcellulose (HPMC) by NMR spectroscopy and NMR imaging techniques. Macromolecules 1997 30(20) 6230-6237. 

Tritt-Goc J, Pislewski N. Magnetic resonance imaging study of the swelling kinetics of hydroxypropylmethylcellulose (HPMC) in water. J Control Release 2(X)2 80(l-3) 79-86. 

Hydroxypropylmethylcellulose (HPMC) Soluble in water Masking taste moisture barrier for immediate-release dosage forms Mostly sold as preprepared formulations, including plasticisers and colourants... 

Hypromellose or hydroxypropylmethylcellulose (HPMC) is a semisynthetic, inert, viscoelastic polymer, which is used as an ophthalmic lubricant, an excipient and controlled delivery component in oral medicaments and is found in a variety of commercial products [111]. Hypromellose is used as an alternative to animal gelatin and as an emulsifier, thickener, and suspending agent. 

Figure 4 shows the of lyophilized formulations containing various polymer excipients as a function of relative humidity [26], As relative hymidity increased, for each formulation decreased. Formulations containing a, S-poly (vV-hydroxyethyl)-L-aspartamide (PHEA), methylcellu-lose (MC), and hydroxypropylmethylcellulose (HPMC) exhibited comparable r io values at lower humidities than formulations with dextran and carboxymethylcellulose sodium salt (CMC-Na). This indieates that the formulations containing PHEA, MC, and HPMC contain highly mobile protons at a lower temperature than the formulations containing dextran and CMC-Na at the same humidity. 

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