Excipient Profile of Carbopol 934: Carbopol 934 is a high molecular weight cross-linked polymer of acrylic acid, is a versatile pharmaceutical excipient extensively used in the formulation of a variety of dosage forms. This article aims to provide a comprehensive review of the excipient profile of Carbopol 934, focusing on its role in drug delivery systems and its interaction with other excipients.
Excipient Profile of Carbopol 934
Carbopol 934 in Drug Delivery Systems
Carbopol 934 plays a significant role in the formulation of various drug delivery systems. One such application is in the creation of mucoadhesive buccal tablets.
A 2021 study investigated the formulation and characterization of mucoadhesive buccal tablets of aceclofenac, utilizing different proportions of three polymers including Carbopol 934. The research found that the tablets exhibited acceptable physicochemical parameters and ensured sustained and effective release.
Another application of Carbopol 934 is in the formulation of sustained release matrix tablets. A 2021 study focused on the formulation and evaluation of sustained release matrix tablets of Itopride using Carbopol 934 among other polymers. The study concluded that the drug release profile was well controlled and uniform throughout the dissolution studies.
Carbopol 934 and Other Excipients
The interaction between Carbopol 934 and other excipients is a crucial aspect of drug formulation. A 2019 study reported a case of chronic inflammatory granulomata due to Carbopol 980 excipient, highlighting the importance of understanding the interactions and potential side effects of Carbopol with other excipients.
Novel Carbopol 934 Excipients
The development of novel Carbopol 934 excipients continues to be a focus in pharmaceutical research. A 2017 study investigated the preparation and evaluation of Carbopol coated maize starch as a novel multifunctional excipient. The research found that the new excipient showed promising characteristics for drug delivery applications.
Chemical Structure
Carbopol 934 is a lightly cross-linked polymer of acrylic acid. The cross-linking is achieved through the use of allyl ethers of pentaerythritol. The polymer chains in Carbopol 934 are in a random coil configuration, but when dispersed in water, they uncoil and hydrate, causing the solution to thicken.
Physical and Chemical Properties
- Appearance: Carbopol 934 is a white, fluffy, acidic, hygroscopic powder with a slight acetic acid odor.
- Solubility: It is soluble in water and, to a lesser extent, in alcohol. It swells up to 1000 times its original volume when dispersed in water, creating a colloidal, mucilage-like dispersion.
- pH: The pH of a 0.5% aqueous dispersion of Carbopol 934 is in the range of 2.5 to 3.0. However, when neutralized with an appropriate base, it forms a gel with a pH of about 7.5.
- Viscosity: The viscosity of Carbopol 934 is greatly influenced by the pH of the solution. It exhibits maximum viscosity at a pH of around 7.5.
- Melting Point: Carbopol 934 decomposes without melting at high temperatures.
- Molecular Weight: The molecular weight of Carbopol 934 is approximately 3 million Daltons.
Excipient Profile of Carbopol 934
| Property | Description |
|---|---|
| Binder | Used as a binder in tablet formulations due to its ability to form a gel layer that holds the tablet together. |
| Controlled-Release Agent | Used in the formulation of controlled-release dosage forms. The rate of drug release can be controlled by adjusting the concentration and cross-linking of Carbopol 934. |
| Film Coating Agent | Forms a smooth, transparent, and glossy film that is resistant to cracking. The film can mask the taste and odor of the drug, protect the drug from moisture and light, enhance the appearance of the tablet, and provide a surface for printing. |
| Thickening Agent | Increases the viscosity of semi-solid and liquid formulations, improving their stability and texture. |
| Stabilizer | Acts as a stabilizer in suspensions and emulsions, preventing the settling or aggregation of particles. |
| Mucoadhesive Agent | Exhibits excellent mucoadhesive properties, making it useful in the formulation of buccal, nasal, ocular, and vaginal drug delivery systems. |
| Gelling Agent | Forms gels when dispersed in water and neutralized with a base. The gels are clear, highly viscous, and stable over a wide range of temperatures and pH levels. |
| Suspending Agent | Used as a suspending agent in pharmaceutical suspensions, maintaining the uniform dispersion of insoluble drug particles. |
| Emulsifying Agent | Acts as an emulsifying agent in oil-in-water emulsions, stabilizing the emulsion by reducing interfacial tension and forming a gel network. |
Chemical Properties of Carbopol 934
| Property | Description |
|---|---|
| Chemical Formula | (C3H4O2)n (polymer of acrylic acid) |
| Molecular Weight | Approximately 3 million Daltons |
| Appearance | White, fluffy, acidic, hygroscopic powder |
| Odor | Slight acetic acid odor |
| Solubility | Soluble in water, forms a viscous colloidal solution. Partially soluble in alcohol |
| Melting Point | Decomposes without melting at high temperatures |
| pH | The pH of a 0.5% aqueous dispersion is in the range of 2.5 to 3.0. However, when neutralized with a base, it forms a gel with a pH of about 7.5 |
| Viscosity | Depends on the pH of the solution. Exhibits maximum viscosity at a pH of around 7.5 |
| Hygroscopicity | Yes, absorbs moisture from the air |
Please note that the properties of Carbopol 934 can vary depending on the specific grade and the manufacturer. Always refer to the manufacturer’s data sheet for precise information.
Safety Profile
Carbopol 934 is generally considered safe for use in pharmaceutical applications. It is non-toxic and non-irritating in the concentrations used in pharmaceutical formulations. However, it should be used with caution in formulations intended for mucosal surfaces, as it can cause a transient stinging sensation.
Please note that the properties of Carbopol 934 can vary depending on the specific grade and the manufacturer. Always refer to the manufacturer’s data sheet for precise information.
Gel Formation
One of the most significant properties of Carbopol 934 is its ability to form gels. When dispersed in water and neutralized with a base such as sodium hydroxide or triethanolamine, Carbopol 934 swells and forms a gel.
The gel formation is due to the uncoiling and hydration of the polymer chains, which create a three-dimensional network that entraps water molecules. The resulting gel is clear, highly viscous, and stable over a wide range of temperatures and pH levels.
Rheology
Carbopol 934 exhibits pseudoplastic or shear-thinning behavior. This means that its viscosity decreases with increasing shear rate. This property is beneficial in applications such as topical formulations, where the product needs to be easy to apply but should stay in place once applied.
Bioadhesion
Carbopol 934 has excellent bioadhesive properties. It can adhere to mucosal surfaces, which makes it useful in the formulation of mucoadhesive drug delivery systems. The bioadhesive property of Carbopol 934 is due to the formation of hydrogen bonds between the polymer and the mucin present in mucus.
Suspending Agent
Carbopol 934 is used as a suspending agent in pharmaceutical suspensions. It helps to maintain the uniform dispersion of insoluble drug particles in the liquid medium. The high viscosity and yield value of Carbopol 934 gels prevent the settling of particles under the influence of gravity.
Emulsifying Agent
Carbopol 934 can also act as an emulsifying agent in oil-in-water emulsions. It helps to stabilize the emulsion by reducing the interfacial tension between the oil and water phases and by forming a gel network that entraps the oil droplets.
Conclusion
The unique chemical properties of Carbopol 934, including its ability to form gels, its pseudoplastic behavior, its bioadhesive properties, and its effectiveness as a suspending and emulsifying agent, make it a versatile and valuable excipient in the pharmaceutical industry. Its safety and compatibility with a wide range of active ingredients and other excipients further enhance its utility in drug formulation.
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