carbopol
physical characteristics
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The Carbopol resins are hydrophilic substances that are not soluble in water. Rather, these polymers swell when dispersed in water forming a colloidal, mucilage-like dispersion.
Carbopol polymers are bearing very good water sorption property. They swell in water up to 1000 times their original volume and 10 times their original diameter to form a gel when exposed to a pH environment above 4.0 to 6.0
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Applications of Carbopol polymers:
The readily water-swellable Carbopol polymers are used in a diverse range of pharmaceutical applications to provide:
• Controlled release in tablets.
• Bioadhesion in buccal, ophthalmic, intestinal, nasal, vaginal and rectal applications.
• Thickening at very low concentrations to produce a wide range of viscosities and flow properties in topical, lotions, creams and gels, oral suspensions and transdermal gel reservoirs.
• Permanent suspensions of insoluble ingredients in oral suspensions and topicals
• Emulsifying topical oil-in-water systems permanently, even at elevated
temperatures, with essentially no need for irritating surfactants.
Topical Applications:
Carbomers are very well suited to aqueous formulations of the topical dosage
forms. Many commercial topical products available today have been formulated
with these polymers,
as they provide the following numerous benefits to topical
formulations:
• Safe & Effective — Carbopol polymers have a long history of safe and effective use in topical gels, creams, lotions, and ointments. They are also supported by extensive toxicology studies.
• Non-Sensitizing — Carbopol polymers have been shown to have extremely low irritancy properties and are non-sensitizing with repeat usage.
• No Effect on the Biological Activity of the Drug — Carbopol polymers provide an excellent vehicle for drug delivery. Due to their extremely high molecular weight, they cannot penetrate the skin or affect the activity of the drug.
• Excellent Thickening, Suspending, & Emulsification Properties for Topical Formulations
Products with a wide range of viscosities and flow properties have been successfully formulated and commercialized. Carbopol polymers are used to permanently suspend the active ingredients in transdermal reservoirs as well as in topical gels and creams. Pemulen polymeric emulsifiers can be used to prepare stable emulsions, such as turpentine liniment, without the use of surfactants. Carbopol polymers and Pemulen polymeric emulsifiers are often the thickener and emulsifier of choice in topical lotions.
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