Hydroxypropyl methyl cellulose

Hydroxypropyl methyl cellulose is propylene glycol ether of methyl cellulose, hydroxypropyl and methyl combine with anhydrous glucose ring by ether bond.It is white or pale white cellulose powder or particles. The characteristics of cold water dissolution and hot water insoluble are similar with methyl cellulose. Solubility in organic solvents is superior than water soluble, can be dissolved in anhydrous methanol and ethanol solution, also soluble in chlorinated hydrocarbons and ketones in organic solvents. Soluble in water, its water solution has a surface activity, the formation of the film after drying, heated and cooled, in turn, from the reversible conversion of sol to gel. Can be used alone in the cold drink, also can be used with other emulsifier, stabilizer. To cold drink, the maximum amount is 1%. Hydroxypropyl methyl cellulose and other water-soluble high weight compounds use mixture, become transparent, higher viscosity. The gelation temperature of low viscosity products is higher than high viscosity of products. Its solution is stable at room temperature. In recent years, It has been widely used in petroleum chemical industry, papermaking, leather, textile printing and dyeing, pharmaceutical, food, cosmetics and other industries, and as the dispersing agent, thickening agent, adhesive, excipient, capsule, oil resistant coating and packing etc.

Figure 1 The molecular structure of hydroxypropyl methyl cellulose

Hydroxypropyl methyl cellulose is propylene glycol ether of methyl cellulose, hydroxypropyl and methyl combine with anhydrous glucose ring by ether bond.It is white or pale white cellulose powder or particles.It has different types of products, the methoxy and hydroxypropyl content ratio is different. It is white or gray fibrous powder or particles. It is soluble in water and some organic solvents and unsoluble in ethanol. Aqueous solution has a surface activity, the formation of the film after drying, heated and cooled, in turn, from the sol to gel reversible transformation.

Hydroxypropyl Methyl Cellulose (HPMC) are water soluble polymers derived from cellulose. They are typically used as thickeners, binders, film formers, and water retention agents. They also function as suspension aids, surfactants, lubricants, protective colloids, and emulsifiers. In addition, solutions of these polymers thermally gel.
hydroxypropyl methyl cellulose has many excellent properties. lt is presented below some examples of HPMC applications:
Food industry: stabilizers of emulsions and foams, as a replacement for fat, as a non-caloric bulking agentin foods, as a binder, among others.
Pharmaceutical industry: as a dispersing and thickening agent, film-coating of tablets, drug preparations,among others.
Cosmetics industry: hair shampoo, eye makeup, skin care preparations, among others.

Hydroxypropyl methyl cellulose and methyl cellulose are also water-soluble nonionic polymers. They are compatible with inorganic salts and ionic species up to a certain concentration. Methyl cellulose can be salted out of solution when the concentration of electrolytes or other dissolved materials exceeds certain limits. Hydroxypropyl methyl cellulose has a higher tolerance for salts in solution than methyl cellulose. Both are stable over a pH range of 3 to 11. Commercial water-soluble methyl cellulose products have a methoxy DS of 1.64 to 1.92. A DS of lower than 1.64 yields material with lower water solubility.The methoxy DS in hydroxypropyl methyl cellulose ranges from 1.3 to 2. Thehydroxypropyl MS ranges from 0.13 to 0.82. Methyl cellulose and hydroxypropyl methyl cellulose polymers have a number of applications and are used as thickeners in latex paints,food products,shampoos,creams and lotions, and cleansing gels. U.S.Patent 5,565,421 is an example of the use of hydroxypropylmethyl cellulose polymer to gel a light-duty liquid detergent containing anionic surfactants.

It is soluble in water swelling, forming a transparent milky white sticky gel solution, and insoluble in ethanol.

ADI does not make special provisions (FAO/WHO, 2001). It can be used for food safety (FDA. §172.87, 2000). LD505200mg/kg (rats, intra peritoneal injection).

FAO/WHO (1984): Cold drink ,10g/kg (in the end product design, single use or with other emulsifier, stabilizer and thickener dosage).
GB 2760-96: all kinds of food, to GMP limited.

Hydroxypropyl methyl cellulose is obtained by treatment of fibrous plant material with alkali, methyl chloride and propylene oxide.
1.The refined cotton cellulose with alkali treatment at 35-40 ℃ for half an hour, press, crushed the cellulose, aging at 35 ℃, so that the average degree of polymerization of alkali cellulose is in a desired range. The alkali fiber into etherification reactor, followed by adding epoxy propane and methane chloride, etherification at 50-80 ℃ for 5h, the maximum pressure is about 1.8MPa. The reaction products were produced by postprocessing (hydrochloric acid and oxalic acid, washing and drying). The consumption of raw material of cotton pulp 1100kg/t, methyl chloride and propylene oxide 4300kg/t, solid alkali 1200kg/t, hydrochloride 30kg/t, oxalic acid 50kg/t.
2.100 kg refined cotton linters immersed in 45% solution, temperature is 35 to 40℃, time is 0.5 to 1 h, and then remove the press. The pressure to weight is 2.7 times as the weight of lint, stop pressure. Carry out the crushing. At 35℃, aging for 16h.
In the reaction kettle, the chlorinated methane, propylene oxide were added into the reaction kettle. At 80℃, the pressure was 1.8 MPa, the reaction time is 5 to 8 h, and the amount of hydrochloric acid and oxalic acid were added to the hot water at 90℃. Dewatering with centrifuge, washing to neutral, when the water content of the material is below to 60% , 130℃ of hot air flow dried to the moisture content is below 5%. Finally, the finished product sieved by 20 mesh.
3. Prepared by cellulose, methyl chloride, and ethylene oxide.

Hydroxypropyl methyl cellulose is a propylene glycol ether of methylcellulose in which both hydroxypropyl and methyl groups are bound to the anhydrous glucose ring of cellulose by ether linkages. Hydroxypropyl methyl cellulose is synthesized from methyl cellulose by the action of alkali and propylene oxide. The resultant product is a water soluble ether derivative of cellulose containing both methoxy and hydroxypropyl groups. The degree of substitution is 1.08 to 1.83 with the hydroxypropyl groups as the minor constituent. White to off-white fibrous powder or granules. Soluble in water and some organic solvents. Insoluble in ethanol, the aqueous solution has surface activity, forms a thin film after drying, and undergoes a reversible transition from sol to gel in turn by heating and cooling.

Hypromellose is an odorless and tasteless, white or creamy-white fibrous or granular powder. This product is soluble in water (10 mg/ml). However, it is very important to thoroughly disperse the particles in water with agitation before they will dissolve. Otherwise, they will lump and form a gelatinous membrane around the internal particles, preventing them from wetting completely. There are four dispersion techniques commonly used to prepare solutions of hydroxypropylmethylcellulose: dispersion in hot water, dry blending, dispersion in non-solvent medium, and dispersion of surface-treated powders.

Hydroxypropyl Methylcellulose is a gum formed by the reaction of propylene oxide and methyl chloride with alkali cellulose. it will gel as the temperature is increased in heating and upon cooling will liquefy. the gel temperature ranges from 60°c to 90°c, forming semifirm to mushy gels. it is used in bakery goods, dressings, breaded foods, and salad dressing mix for syneresis control, texture, and to provide hot viscosity. usage level ranges from 0.05 to 1.0%.

A purified form of cellulose, obtained from cotton linters or wood pulp, is reacted with sodium hydroxide solution to produce a swollen alkali cellulose that is chemically more reactive than untreated cellulose. The alkali cellulose is then treated with chloromethane and propylene oxide to produce methyl hydroxypropyl ethers of cellulose. The fibrous reaction product is then purified and ground to a fine, uniform powder or granules. Hypromellose can then be exposed to anhydrous hydrogen chloride to induce depolymerization, thus producing low viscosity grades.

Hydroxypropyl methyl cellulose is used as an ophthalmic lubricant, an emulsifier and a thickening and suspending agent. It is widely used as an excipient in pharmaceutical formulations. It acts as a food additive. Its eye drops are known as artificial tears, which are used to relieve eye dryness and soreness. It finds applications in various fields as emulsifier, film former, protective colloid, stabilizer, suspending agent, or thickener in foods. Pharmaceutic aid (suspending agent; tablet excipient; demulcent; viscosity increasing agent); hydrophilic carrier in drug delivery systems. In adhesives, asphalt emulsions, caulking compounds, tile mortars, plastic mixes, cements, paints.

Hydroxypropyl methylcellulose belongs to the group of medicines known as artificial tears. It is used to relieve dryness and irritation caused by reduced tear flow. It helps prevent damage to the eye in certain eye diseases. Hydroxypropyl methylcellulose may also be used to moisten hard contact lenses and artificial eyes. In addition, it may be used in certain eye examinations.

Hydroxypropylmethylcelluloses are water soluble polymers derived from cellulose. They are typically used as thickeners, binders, film formers, and water retention agents. They also function as suspension aids, surfactants, lubricants, protective colloids, and emulsifiers. In addition, solutions of these polymers thermally gel.
These polymers are prepared by reacting wood or cotton cellulose fibers with propylene oxide and methyl chloride in the presence of caustic soda. This product has a methoxyl content of 28-30% and a hydroxypropoxyl content of 7-12%.

Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug.
Major & minor side effects for Hydroxypropyl Methylcellulose
Blurred vision
Decrease/loss of vision
Eye pain
Excessive tearing of the eye
Redness in and around the eyes

Hypromellose is widely used as an excipient in oral, opthalmic, nasal, and topical pharmaceutical formulations. It is also used extensively in cosmetics and food products.
Hypromellose is generally regarded as a nontoxic and nonirritating material, although excessive oral consumption may have a laxative effect. The WHO has not specified an acceptable daily intake for hypromellose since the levels consumed were not considered to represent a hazard to health. In fact, high dosages of hypromellose are being investigated for treating various metabolic syndromes.
LD50 (mouse, IP): 5 g/kg(20) LD50 (rat, IP): 5.2 g/kg

Hypromellose powder is a stable material, although it is hygroscopic after drying.
Solutions are stable at pH 3–11. Hypromellose undergoes a reversible sol–gel transformation upon heating and cooling, respectively. The gelation temperature is 50–90°C, depending upon the grade and concentration of material. For temperatures below the gelation temperature, viscosity of the solution decreases as temperature is increased. Beyond the gelation temperature, viscosity increases as temperature is increased.
Aqueous solutions are comparatively enzyme-resistant, providing good viscosity stability during long-term storage. However, aqueous solutions are liable to microbial spoilage and should be preserved with an antimicrobial preservative: when hypromellose is used as a viscosity-increasing agent in ophthalmic solutions, benzalkonium chloride is commonly used as the preservative. Aqueous solutions may also be sterilized by autoclaving; the coagulated polymer must be redispersed on cooling by shaking.
Hypromellose powder should be stored in a well-closed container, in a cool, dry place.

Hypromellose is incompatible with some oxidizing agents. Since it is nonionic, hypromellose will not complex with metallic salts or ionic organics to form insoluble precipitates.

GRAS listed. Accepted for use as a food additive in Europe. Included in the FDA Inactive Ingredients Database (ophthalmic and nasal preparations; oral capsules, suspensions, syrups, and tablets;topical and vaginal preparations). Included in nonparenteral medicines licensed in the UK. Included in the Canadian List of Acceptable Non-medicinal Ingredients.