IngredientsThe term Carbopol is a registered trade name, not a naturally derived botanical or dietary ingredient in the traditional sense. It is a fully synthetic polymer whose role in the dietary supplement context is exclusively that of a functional excipient — a carrier, suspending agent, controlled-release matrix, or viscosity modifier — rather than an active therapeutic agent. The EFSA Panel on Food Additives and Flavourings (FAF) has evaluated crosslinked polyacrylic acid polymers (carbomer/Carbopol) specifically proposed for use as a food additive in solid and liquid food supplements. This reference article covers its chemical identity, regulatory standing, functional mechanisms, and all available safety data in that context.
Carbomer is the generic (i.e., nonproprietary) name adopted by the USP-NF, the United States Adopted Names Council (USAN), and the CTFA (Cosmetic, Toiletry and Fragrance Association) for various Carbopol™ polymers. Such polymers also go by the names acritamer or carbopol. The chemical name and CAS registry number for the class is carboxypolymethylene [54182-57-9].
Carbomer (CP) is also known as carbopol or carboxy-polymethylene. Additional synonyms found in the literature include carboxyvinyl polymer and polyacrylic acid (crosslinked). Carbomers are synthetic, high-molecular-weight, nonlinear polymers of acrylic acid, cross-linked with a polyalkenyl polyether.
Carbopol has no botanical or natural origin. Carbopol Polymers are synthetic polymers of acrylic acid with high molecular weight used to increase the viscosity and modify the rheological features of liquid or semisolid formulations. The proposed food additive 'carbomer' is formed from the monomer, acrylic acid, which is polymerised and crosslinked with allyl pentaerythritol (APE). The polymers are synthesised in ethyl acetate using a free-radical polymerisation initiator.
The original synthetic powdered alkali-swellable carbomer was trademarked as Carbopol (US patent 2798503) and commercialized in 1958 by BF Goodrich (now known as Lubrizol). Although carbopol was patented in 1957, it was first discussed in scientific literature in 1955.
Products within the Carbopol polymer family are chemically similar in that they are all high-molecular-weight, crosslinked polyacrylic acid polymers. However, these gel-forming polymers differ by their chemical crosslinking. Each polymer differs based on the extent of cross-link density, allowing for two categories: Carbopol homopolymers, in which acrylic acid is cross-linked with allyl sucrose or allyl pentaerythritol; and Carbopol copolymers, in which acrylic acid and C-10, C-30 alkyl acrylates are cross-linked with allyl pentaerythritol.
They are produced from primary polymer particles of about 0.2 to 6.0 microns average diameter. The flocculated agglomerates cannot be broken into the ultimate particles when produced. Each particle can be viewed as a network structure of polymer chains interconnected via cross-linking.
The three grades evaluated by EFSA for food supplement use are specifically identified: The applicant indicated that three different grades of the carbomer are produced and sold under the trade names Carbopol® 974P NF Polymer, Carbopol® 971P NF Polymer, and Carbopol® 71G NF Polymer. Specifically, two grades can be manufactured by varying the amount of the crosslinker APE used in the polymerisation reaction — Carbopol® 974P NF Polymer, defined as 'highly crosslinked', and Carbopol® 971P NF Polymer, defined as 'lightly crosslinked' — thus resulting in polymers with different viscosities. A third grade (Carbopol® 71G NF Polymer) can be obtained from Carbopol® 971P NF Polymer via dry granulation to give a different particle size.
The estimated average molecular weight of the three carbomer grades is over 3 Ă— 109 Daltons (Da), but an amount of lower molecular weight fraction (LMWF) is present in the final product.
These polymers are offered as fluffy, white, dry powders. When neutralized in water, they form viscous gels. Carbomers are supplied in the acid form and when neutralized by the end user form aqueous gels at low concentrations of around 0.5% w/v. The acid form of the polymer is also very viscous, but not as viscous as the neutralized form.
Carbomer was first produced by Goodrich Company in the United States. It has been included in the 23rd edition of the United States Pharmacopoeia and has been widely used in the development and production of drugs and cosmetics. Lubrizol's benzene-polymerized polymers do not meet the European Pharmacopoeial "Carbomers" monograph because the residual benzene levels exceed the 2 ppm limit stipulated in the monograph. As a result, alternative manufacturing processes have been developed to comply with European regulatory requirements.
Carbopol does not have a history of traditional ethnobotanical or folk-medicine use; it is a mid-twentieth-century industrial invention. Carbopol polymers were first described in scientific literature back in 1955. Carbomers were first prepared and patented in 1957. Since then, a number of extended-release tablet formulations involving carbomer matrices have been patented.
The original synthetic powdered alkali-swellable carbomer was trademarked as Carbopol (US patent 2798503) and commercialized in 1958 by BF Goodrich (now known as Lubrizol). Carbopol 940, 941, and 934 were breakthrough technologies that revolutionized how personal care products are formulated and created new types of products that were previously not possible to make.
Since their creation as the first commercial carbomers over 50 years ago, Lubrizol's Carbopol® polymers have continued to be widely used in pharmaceutical products as rheology modifiers, tablet binders, suspension stabilizers, extended-release polymers, mucoadhesive aids, and bioavailability enhancers.
Today, Carbopol polymers are widely accepted ingredients in pharmaceutical dosage systems of almost every form, from controlled-release tablets to oral suspensions to novel delivery systems, as well as a variety of topical products.
Early manufacturing of certain Carbopol grades used benzene as a polymerisation solvent. Traditional carbomers are synthesized in benzene, a substance that is increasingly restricted for use in pharmaceutical excipient applications. The introduction of legislation against toxic waste has led to polymerisation in alternative solvents. Such resins may contain very small amounts of a mixture of ethyl acetate and cyclohexane as an innocuous cosolvent and solvent, respectively. The grades now approved for food supplement use in the European Union are specifically those synthesized without benzene.
Carbopol® is a water-soluble polymer used to emulsify and/or stabilize products, or in drugs and dietary supplements for controlled release of the primary ingredient. Its appearance on dietary supplement labels is therefore as a delivery vehicle, not as a bioactive phytochemical. The only two ingredients listed on the Supplement Facts panel of one identified product were Carbopol® and 5α-hydroxy laxogenin. This illustrates the typical context: Carbopol serves to control the release or stabilize the principal active substance.
The carboxyl groups provided by the acrylic acid backbone of the polymer are responsible for many of the product benefits. Although these polymers are very mild acids — weaker than acetic acid — they readily react with alkali to form salts.
The carbomer impurities profile was characterised by the applicant showing that they are substances carried over or originated from the starting materials, i.e., residual acrylic acid, residual ethyl acetate, unreacted APE, or by-products from the polymerisation initiator.
Carbopol polymers provide a wide range of viscosity profiles and have very high yield values, even at low concentrations, thus being very effective suspending agents for formulating oral suspensions.
Carbopols such as Carbopol 971P NF, Carbopol 910, and Carbopol 941 are classified as low-viscosity gelling agents, with viscosity grades ranging from 3,000 to 10,000 centipoises. These properties allow for the formation of gels with high clarity and less consistency, making them suitable for controlled-release formulations.
In contrast to linear polymers, higher viscosity does not result in slower drug release with carbomers. Lightly crosslinked carbomers (lower viscosity) are generally more efficient in controlling drug release than highly crosslinked carbomers (higher viscosity).
When carbomer tablets are placed in contact with dissolution media, the external surface of the tablet becomes hydrated. It then swells and forms a gel layer that efficiently controls the release of the drug from the tablets. Due to the crosslinked nature of the polymer, the hydrogel is not composed of single entangled chains of polymer (as in water-soluble polymeric matrices), but discrete microgels made up of many polymer particles in which the drug is dispersed. Because carbomer is not water soluble, it does not dissolve, and erosion in the manner of linear polymers such as HPMC does not occur.
When the beads are placed in a pH 7.4 dissolution medium, they hydrate, causing carbopol to form carboxylate ions by losing protons. The resulting repulsion between the carboxylate ions causes swelling and gel formation, which acts as a rate-controlling factor for drug release. The most likely release mechanism was reported to be the electrostatic interaction between the anionic carboxylate groups on carbopol and the cationic nature of the drug, with additional contributions from swelling and gelling effects due to ionic strength.
Carbomers readily absorb water, get hydrated, and swell. In addition to its hydrophilic nature, its cross-linked structure and essential insolubility in water makes Carbopol a potential candidate for use in controlled-release drug delivery systems.
Carbomers are extensively being used in controlled drug delivery systems (CDDS). They are also finding numerous applications in oral mucoadhesive drug delivery because of their ability to interact with the mucus glycoprotein and to remain localized to a specific site.
In the case of polymers such as carbopols, which have a very high affinity for water, holding the formulation on the surface of the mucus layer is observed. Two types of interactions occur between the mucoadhesive polymer and the mucus layer: (1) attractive forces such as van der Waals forces and hydrogen bonding, and (2) electrostatic interactions between the negatively charged groups on the mucin and the positive charge on the polymers.
Following a request from the European Commission to the European Food Safety Authority (EFSA), the Panel on Food Additives and Flavourings (FAF) was asked to provide a scientific opinion on the safety of crosslinked polyacrylic acid polymers (carbomer) proposed for use as food additive in solid and liquid food supplements, in accordance with Regulation (EC) No 1331/2008 establishing a common authorisation procedure for food additives, food enzymes and food flavourings.
On 1 March 2023, the European Official Journal published an amendment that adds carbomer (E 1210) to the EU List of Authorized Food Additives and approves it for use in food supplements. The 2023 European Food Safety Authority (EFSA) approval of Carbopol polymers as a food additive (E 1210) in Europe will enable manufacturers to make new product claims.
All these grades of Carbopol polymers are IID (Inactive Ingredient Database)-listed ingredients used in FDA-approved oral drug products. Their strong precedence of use in the oral space facilitates their use in novel extended-release tablets and 505(b)(2) products. Carbopol is listed in the US National Formulary (NF) under the Carbomer monograph. However, it is not specifically approved by the FDA as a dietary supplement ingredient with an established health claim; it functions as a permitted excipient.
The safety of carbomers was assessed by the American College of Toxicology in 1982 and reevaluated in 2002; the conclusion was that carbomers are safe for use in humans.
Carbomer having low residuals of ethyl acetate, such as Carbopol 971P NF or Carbopol 974P NF, may be used in oral preparations, including suspensions, capsules, or tablets. In tablet formulations, carbomers are used as controlled-release agents and/or as binders.
Regarding typical use levels in oral solid dosage forms: Carbopol is highly efficient at low polymer levels, with typical use levels of 5–30%, enabling smaller tablet sizes overall. For water-soluble drugs specifically, 10% powder-grade polymer or 25% granular-grade polymer is a good starting concentration.
It is used as a direct-compressible excipient in controlled-release tablets. There is also a granular form of carbomer called Carbopol 71G polymer, which is free-flowing and directly compressible, leading to simplified processing.
Case studies show Carbopol polymers can be of great benefit for conferring sustained release to metformin formulations, as well as reducing tablet size by 20%–30%.
Carbopol polymers provide a wide range of viscosity profiles and have very high yield values, even at low concentrations, thus being very effective suspending agents for formulating oral suspensions. Typical use levels in suspending applications are reported in formulation guides as 0.1–1%.
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, and thickening at very low concentrations to produce a wide range of viscosities and flow properties in topical lotions, creams, gels, oral suspensions, and transdermal gel reservoirs.
Typical formulation concentrations for topical pharmaceutical uses, as reported in published formulation data, are: as a gelling agent, 0.5–2%; as an emulsifying agent, 0.1–0.5%; as a suspending agent, 0.1–1%; as a binder in tablets, 0.75–3%; as a controlled-release agent, 5–30%; in aqueous ointments or base gels, 0.5–5%; and in artificial tears, 0.2–0.3%.
A 2023 systematic review evaluated Carbopol in topical mucoadhesive drug delivery. A systematic searching strategy was performed in Scopus, ProQuest, and PubMed databases using predetermined search strings. A total of 778 articles were retrieved; however, only 25 articles met the inclusion criteria and were used for data synthesis. The evidence base at that level is predominantly preclinical and formulation-focused.
Research has highlighted that adding Ca(OH)2 to formulations containing starch and carbopol significantly enhances insulin bioavailability in the nasal cavity. The optimal insulin absorption in the nasal cavity is likely due to a balance between the cations and the carboxylate groups on the polyacrylate chains. The authors concluded that the key determinant for nasal insulin bioavailability was the formation of a mixed sodium and calcium carboxylate salt of polyacrylic acid. These findings are preclinical and formulation-based.
One preclinical study explored carbopol-based mucoadhesive microspheres: the purpose of the research was to formulate and systematically evaluate in vitro and in vivo performances of mucoadhesive amoxicillin microspheres for the potential use in the treatment of gastric and duodenal ulcers associated with Helicobacter pylori. Amoxicillin mucoadhesive microspheres containing carbopol-934P as mucoadhesive polymer and ethyl cellulose as carrier polymer were prepared by an emulsion-solvent evaporation technique. The best batch exhibited a high drug entrapment efficiency of 56%; mucoadhesion percentage after 1 h was 80%, and the particle size was 109 µm. A sustained drug release was obtained for more than 12 h. This remains preclinical in vitro/in vivo animal evidence.
Carbopol polymer 71G NF is a useful and versatile controlled-release additive for tablet formulations in direct compression. Carbomers act as efficient controlled-release agents for matrix tablets and also improve bioavailability of certain drugs. Along with excellent adhesion forces, they lower the concentration of active ingredient and provide patient compliance with increased bioavailability of certain drugs.
In an animal study examining oral bioavailability of sodium alendronate, the formulation of alendronate in matrix tablets based on Carbopol C 971 resulted in a considerable increase in oral bioavailability. This is a preclinical finding and has not been replicated in large-scale human controlled trials for supplement applications specifically.
Important context: Carbopol is an excipient and not a therapeutic agent. Therefore, the scientific literature does not evaluate it for standalone clinical health outcomes in the same way as bioactive dietary supplement ingredients. The evidence instead covers its functional performance as a delivery system component and its safety as a food additive.
The controlled-release function of carbopol is among the best-characterized properties in pharmaceutical science. In recent decades, there has been considerable interest in using carbopol as an excipient in a diverse range of pharmaceutical applications. Carbopol polymers are polymers of acrylic acid cross-linked with polyalkenyl ethers or divinyl glycol. They are produced from primary polymer particles of about 0.2 to 6.0 microns average diameter. The flocculated agglomerates cannot be broken into the ultimate particles when produced. Each particle can be viewed as a network structure of polymer chains interconnected via cross-linking. Carbomers readily absorb water, get hydrated, and swell.
The drug-release kinetics from carbopol-based matrices have been studied extensively in vitro and in animal models. Drug release from matrix tablets follows diffusion and erosion mechanisms dependent on the polymer's swelling. The release period in one glipizide microsphere system was extended to 18 h. In vitro release of the drug from the beads followed the diffusion and erosion mechanism. These findings are laboratory-based; no large-scale human clinical trials have specifically evaluated carbopol as a supplement excipient for controlled-release performance independent of a specific active drug.
Carbomer, also known as Carbopol, is a mucoadhesive polymer that is widely studied for topical delivery of pharmaceutical agents to the mucous membrane. The use of Carbopol and its advantages in the mucoadhesive topical application has gained considerable interest with several published studies and is available in various grades.
The mucoadhesive mechanism is well characterized: Carbomers are extensively being used in controlled drug delivery systems. They are also finding numerous applications in oral mucoadhesive drug delivery because of their ability to interact with the mucus glycoprotein and to remain localized to a specific site. The use of carbomers in oral delivery of peptides or protein-based drugs is also covered in the peer-reviewed literature. Evidence at the human clinical level specific to Carbopol as a food supplement excipient remains limited; most data derive from pharmaceutical drug delivery research.
Carbomers are carboxyvinylic derivatives that are widely used in the manufacture of hydrogel dosage forms. Because of their anionic nature and large number of acid groups, they tend to interact with cationic substances, and with other hydrophilic polymers containing alcohol groups. A study of interactions between the carbomer Carbopol and the cationic drug propranolol hydrochloride in the solid state and in solution found that the drug forms an insoluble ionic complex with the polymer, modifying all of the hydrogel properties studied (swelling, release, bioadhesion). This indicates that formulators must account for interactions between carbopol and cationic active ingredients when designing supplement products.
De Clercq and Luczak (1976) described antiviral activity of Carbopol, a cross-linked polycarboxylate, published in Archives of Virology 52(1-2):151–58. This early study is in vitro and represents highly preliminary evidence with no established clinical relevance for dietary supplement use.
Cahen, Groskinsky, and Lesson (1958) published findings on the pharmacological effects of carboxyvinyl polymer as a bulk laxative. This historical reference has not been developed into modern clinical evidence, and carbopol's laxative characterization is not reflected in current regulatory approvals for food supplement use.
As an excipient, Carbopol is associated with delivery to virtually every body system and mucosal surface. These systems can be administered by oral, parenteral, and topical routes as platforms for delivery of biologically active agents from different origins such as mineral, animal, or vegetal. Specifically documented routes and systems include:
The following concentrations are sourced from published pharmaceutical formulation references and regulatory filings. They represent use levels of Carbopol as an excipient within a product, not doses of a standalone supplement ingredient:
With respect to the regulatory acceptable daily intake: the EFSA Panel derived an acceptable daily intake (ADI) of 190 mg/kg body weight (bw) per day based on a no observed adverse effect level (NOAEL) of 1,500 mg/kg bw per day from a sub-chronic 13-week study in rat, applying a compound-specific uncertainty factor (UF) of 8. At the proposed maximum use levels in food supplements, the exposure estimates ranged at the mean from 1.1 to 90.2 mg/kg bw per day and at the 95th percentile from 12.5 to 237.4 mg/kg bw per day.
In vivo data showed no evidence for systemic availability or biotransformation of carbomer. Carbomer does not raise a concern regarding genotoxicity.
Carbomer showed no evidence for systemic availability or biotransformation in an in vivo study in rats dosed by gavage with three 14C-labelled poly(acrylic acid) of different average molecular weights and degrees of cross-linking.
The toxicology data set comprised studies on sub-chronic toxicity (13-week dietary toxicity study in rats; 13-week dietary toxicity study in dogs) and the basic test battery for in vitro genotoxicity.
Overall, the available biological and toxicological data were considered adequate to conclude on the safety of the proposed new food additive.
From the sub-chronic 13-week toxicity study in rats, effects on body weight and body weight gain were observed as well as some minor effects in clinical chemistry parameters. The Panel considered that the decreases in body weight and body weight gain could be reflective of interactions between nutrients and carbomer resulting in nutrient malabsorption, which is considered an undesirable effect. This finding warrants attention in the context of supplement use, particularly at high exposure levels.
The Cosmetic Ingredient Review (CIR) Expert Panel, in their assessment of the safety of carbomers for cosmetic ingredients, summarized that acute oral studies with rats, guinea pigs, mice, and dogs showed that carbomers 910, -934, -940, and -941 have low toxicities when ingested. No mortalities occurred in rabbits injected intravenously with 1%, 2%, or 3% carbomer 934 in aqueous solution at a dose of 5 ml/kg. Rabbits showed minimal skin irritation when tested with 100% carbomer 910 or -934, and zero to moderate eye irritation when tested with carbomers 910, -934, -934P, -940, -941, and/or their various salts at concentrations of 0.20–100%.
The anticipated dietary exposure estimates to the carbomer impurities using the specifications proposed by the applicant and/or the highest reported analytical levels were calculated by the EFSA Panel. For the residual acrylic acid, based on its estimated dietary exposure, the Panel considered that a lowering of the proposed maximum limit for the residual acrylic acid is recommended and it is technologically achievable as indicated by the analytical data provided.
Traditional benzene-synthesized grades carry residual benzene above pharmacopoeial limits. Carbomer having low residuals of other solvents than ICH-defined Class I OVI solvents may be used in Europe. Carbomer having low residuals of ethyl acetate, such as Carbopol 971P NF or Carbopol 974P NF, may be used in oral preparations, including suspensions, capsules, or tablets.
Carbopol 71G-NF is discolored by resorcinol and is incompatible with phenol, cationic polymers, strong acids, and high levels of electrolytes. Certain antimicrobial adjuvants should also be avoided or used at low levels. Carbopol 71G-NF polymer also forms pH-dependent complexes with certain polymeric excipients.
The resulting gels are highly sensitive to the action of electrolytes; thus, they cannot be associated with either anionic and cationic surfactants or with positively charged ions. In contrast, carbopols remain highly stable in their response to variations in temperature.
At the drug interaction level, because of their anionic nature and large number of acid groups, carbomers tend to interact with cationic substances and with other hydrophilic polymers containing alcohol groups. This interaction can alter drug release profiles and bioadhesion characteristics, an important consideration for supplement formulators who co-formulate Carbopol with cationic active ingredients such as certain amino acids, alkaloids, or minerals.
Incompatibilities include: cationic substances (e.g., neomycin sulfate, procaine hydrochloride, diphenhydramine hydrochloride, cationic polymers), electrolytes and metal ions (especially sodium, calcium, aluminum, zinc, magnesium, and iron), strong acids or bases (pH less than 6 or greater than 9–11), phenol, resorcinol, and UV radiation.
Carbopol is a commonly used gelling agent that rarely causes adverse reactions when utilized topically. Its safety for both internal and external administration has been determined following thorough toxicological studies.
Carbomers are safe and effective, non-sensitizing, and do not have any effect on the biological activity of the drug; they are well suited to aqueous formulations of topical dosage forms.
Health conditions that Carbopol may help support.
Body systems that Carbopol may help support.
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