Carbomer has a wide range of applications and can be used in lotions, creams and gels. The carbomer gel system is an excellent gel matrix in a neutral environment. It is crystal clear and smooth to the touch. It is very suitable for the preparation of creams or gels. At the same time, due to the good stability, and comfortable sense after use, therefore, it is widely used in local administration, especially in skin and ophthalmic gels.
Some types of carbomers
1. Carbomer 941. It has the characteristics of long rheology, low viscosity and high-definition clarity, medium ion resistance and shear resistance. It is mainly used for external administration, suitable for external transdermal preparations and high transparency, low viscosity gel emulsion stabilizer for gum, as well as daily washing and cosmetics.
Its advantages are: a. linear drug release (zero-order release kinetics); b. can increase bioavailability; c. low dosage supports slow release; d. cost saving; e. increase the selectivity of formula; f. can reduce the volume of tablets.
The application of carbomer in pharmaceuticals
1. Used as adhesive and film coating material
As a binder for granules and tablets, the amount of carbomer is mainly determined by the physical and chemical properties of the main drug and the prescription design requirements. The general dosage is 5% to 10%.
2. Used as a slow-release skeleton material
Carbomer forms a unique network structure due to covalent cross-linking between chains. It forms a gel after hydration and expansion. It is used as a hydrogel skeleton material in a slow-release control agent and controls the drug through the formed gel layer. Carbomer is used as a slow-release material in a small amount, which can increase the choice of prescription. It is generally 6% to 10% of the prescription, and has excellent compressibility. It has good compatibility with other excipients and can make drugs Zero-order or near-zero-order release (zero-order release: the drug release rate does not change with time, that is, the release rate remains constant during the drug release cycle). The type and amount of carbomer can affect the drug release. Its sustained release effect of 974P is stronger than that of 934P. The tablets containing 10% carbomer 974P and the release rate of 30% 934P are similar. In addition, factors such as the solubility of the drug and the pH of the medium also affect the release of the drug.
3. Used as a base for ointments, suppositories, gels, etc.
The pH of the 1% carbomer solution is about 2.5~3.0. Add alkali regulators such as sodium hydroxide, potassium hydroxide, sodium bicarbonate, borax and triethanolamine. The viscosity increases to form a gel, which is generally the most viscous at pH 6~12. It can be used as the base of water-soluble semi-solid preparations; the dosage is generally 0.5% ~ 3%. The gel matrix releases medicine quickly, has no greasiness, is easy to spread, has no irritation to the skin and mucous membranes, can be mixed with an aqueous solution and can absorb tissue exudate, which is conducive to the elimination of secretions.
4. Used as emulsifier, thickener and suspending agent
Carbomer can be used as an auxiliary emulsifier of O/W type (oil-in-water) emulsifier in the emulsion, the dosage is 0.1%~0.5%; it can be used as a thickener and suspension in the solution and suspension. The dosage commonly used as a gel agent is 0.5%~2%; the dosage used as a suspending agent is 0.5%~1%.
In addition, as a carboxyl polymer, carbomer has strong bioadhesion, of which carbomer 934 has the strongest adhesion. The bioadhesive preparation based on it has been widely used in clinical practice, such as commonly used Nasal bioadhesive, vaginal bioadhesive, rectal bioadhesive, oral or oral bioadhesive, etc.