Description
Hydroxypropyl methyl cellulose(9004-65-3) 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.
Application
Hydroxypropyl methyl cellulose(9004-65-3) 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.
Indications
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.
Production Methods
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.
General Description
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%.
Side effects
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
Safety
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
storage
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.
Incompatibilities
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.
Regulatory Status
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.
