Гидроксипропил целлюлоза

Описание

Hydroxypropyl cellulose is a cellulose ether containing hydroxypropyl substitution. It occurs as a white powder. It is soluble in water and in certain organic solvents. It may contain a suitable anticaking agent.

Химические свойства

Hydroxypropyl cellulose is a white to slightly yellow-colored, odorless and tasteless powder.

Использование

Hydroxypropyl Cellulose is used in the synthesis of nanoparticle carriers for drug delivery.

Определение

A cellulose ether with hydroxypropyl substitution.

Методы производства

A purified form of cellulose is reacted with sodium hydroxide to produce a swollen alkali cellulose that is chemically more reactive than untreated cellulose. The alkali cellulose is then reacted with propylene oxide at elevated temperature and pressure. The propylene oxide can be substituted on the cellulose through an ether linkage at the three reactive hydroxyls present on each anhydroglucose monomer unit of the cellulose chain. Etherification takes place in such a way that hydroxypropyl substituent groups contain almost entirely secondary hydroxyls. The secondary hydroxyl present in the side chain is available for further reaction with the propylene oxide, and ‘chaining-out’ may take place. Thisresults in the formation of side chains containing more than 1 mole of combined propylene oxide.

Общее описание

Hydroxypropyl cellulose (HPC) is biocompatible in nature and exhibits low critical solution temperature (LCST). It has been reported to be prepared by reacting cellulose with alkali, producing alkali cellulose which is consecutively reacted with propylene oxide. HPC is soluble in water at lower than RT. Viscosity behaves inversely to rise in temperature.

Безопасность

Hydroxypropyl cellulose is widely used as an excipient in oral and topical pharmaceutical formulations. It is also used extensively in cosmetics and food products.
Hydroxypropyl cellulose is generally regarded as an essentially nontoxic and nonirritant material. It is not absorbed from the gastrointestinal tract and is fully recovered in feces after oral administration in rats. It does not exhibit skin irritation or skin sensitization. However, the use of hydroxypropyl cellulose as a solid ocular insert has been associated with rare reports of discomfort or irritation, including hypersensitivity and edema of the eyelids. Adverse reactions to hydroxypropyl cellulose are rare. However, it has been reported that a single patient developed contact dermatitis due to hydroxypropyl cellulose in a transdermal estradiol patch. The WHO has specified an acceptable daily intake for
hydroxypropyl cellulose of up to 1500 mg/kg body-weight. Excessive consumption of hydroxypropyl cellulose may have a laxative effect.
LD50 (rat, IV): 0.25 g/kg
LD50 (rat, oral): 10.2 g/kg

хранилище

Hydroxypropyl cellulose powder is a stable material, although it is hygroscopic after drying.
Aqueous solutions of hydroxypropyl cellulose are stable at pH 6.0–8.0, with the viscosity of solutions being relatively unaffected. However, at low pH aqueous solutions may undergo acid hydrolysis, resulting in chain scission and hence a decrease in solution viscosity. The rate of hydrolysis increases with increasing temperature and hydrogen ion concentration. At high pH, alkalicatalyzed oxidation may degrade the polymer and result in a decrease in viscosity of solutions. This degradation can occur owing to the presence of dissolved oxygen or oxidizing agents in a solution.
Increasing temperature causes the viscosity of aqueous solutions to decrease gradually until the viscosity drops suddenly at about 45°C owing to the limited solubility of hydroxypropyl cellulose. However, this process is reversible and on cooling the original viscosity is restored.
The high level of substitution of hydroxypropyl cellulose improves the resistance of the polymer to degradation by molds and bacteria. However, aqueous solutions are susceptible to degradation under severe conditions and a viscosity decrease may occur. Certain enzymes produced by microbial action will degrade hydroxypropyl cellulose in solution. Therefore, for prolonged storage, an antimicrobial preservative should be added to aqueous solutions. Solutions of hydroxypropyl cellulose in organic solvents do not generally require preservatives.
Ultraviolet light will also degrade hydroxypropyl cellulose and aqueous solutions may therefore decrease slightly in viscosity if exposed to light for several months.
Aqueous hydroxypropyl cellulose solutions have optimum stability when the pH is maintained at 6.0–8.0, and also when the solution is protected from light, heat, and the action of microorganisms. Hydroxypropyl cellulose powder should be stored in a wellclosed container in a cool, dry place.

Несовместимости

Hydroxypropyl cellulose in solution demonstrates some incompatibility with substituted phenol derivatives, such as methylparaben and propylparaben. The presence of anionic polymers may increase the viscosity of hydroxypropyl cellulose solutions.
The compatibility of hydroxypropyl cellulose with inorganic salts varies depending upon the salt and its concentration. Hydroxypropyl cellulose may not tolerate high concentrations of other dissolved materials.
The balance of the hydrophilic–lipophilic properties of the polymer, which are required for dual solubility, reduces its ability to hydrate with water and it therefore tends to be salted out in the presence of high concentrations of other dissolved materials.
The precipitation temperature of hydroxypropyl cellulose is lower in the presence of relatively high concentrations of other dissolved materials that compete for the water in the system;

Регуляторный статус

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