Carbomer is a cross-linked acrylic (ester) polymer, which is extensively applied as a rheological modifier in the pharmaceutical, personal care products, and other industrial fields. However, some traditional carbomer products such as 940, 941, 1342, etc. used benzene as solvent during their production, resulting in residual benzene content that could be as high as 5000 ppm, far exceeding the 2 ppm safety limit stipulated by ICH Q3C and USP <467>. Since 2020, the US Food and Drug Administration (FDA) has evaluated the safety of carbomer, and ultimately the US Pharmacopeia (USP) decided to officially omit five type carbomer 940,941,1342, 934, 934P with benzene content greater than 2 ppm from the monograph on August 1, 2025

We, Anhui Newman Fine Chemicals Co., Ltd., as global 2nd largest manufacturer of carbomers, acrylates copolymers and other related polymers, have launched the "Toxicologically Preferred"  NM-Carbomer series .We have not only developed benzene-free carbomer products that use cosolvents instead of benzene as the solvent system, such as NM- Carbomer 970, 20, 21, 990, 981, 1382, 934, 10, 30, etc., but also meets the requirements of major pharmacopoeias of no more than 2mg/kg specified in major pharmacopoeias. Examples of such products include Carbomer homopolymer Type C (NM-Carbomer 970G), Carbomer homopolymer Type A (NM-Carbomer 971P), Carbomer homopolymers Type B (NM-Carbomer 934P, NM-Carbomer 974P), as well as carbomer copolymer and carbomer interpolymer.

Then, what are the differences between NM- Carbomer 934P and NM-Carbomer 974P that belong to Carbomer homopolymer Type B?

I. Similarities between NM-Carbomer 934P and NM-Carbomer 974P

1. Belong to the Carbomer Homopolymer Type B.

2. 0.5wt.% Solution Viscosity (20 rpm at 25ºC, pH @ 7.3~7.8):29,400 ~39,400 mPas

3.Impurity Benzene ≤ 2 ppm

4.Carboxylic Acid content, Assay: 56–68%

5.pH (1% water solution) :2.5–3.5 

II. Differences between NM-Carbomer 934P and NM-Carbomer 974P

1.production processes: Specifically, NM-Carbomer 934P is manufactured via a benzene-free process; whereas NM- Carbomer 974P uses a toxicologically preferred Class III solvent, which features lower toxicity and higher safety.

2.Gel microstructures： After hydration, NM-Carbomer 934P forms a soft elastic gel with fewer channels; by contrast, NM- Carbomer 974P forms a dense "agglomerated" structure with rigid particles and more drug release channels upon hydration.

3.Production Process and Safety y: Adapting to Different Formulation Requirements

Both are P-series oral excipients, and their benzene residue is controlled below 2ppm through process optimization, strictly complying with current pharmaceutical excipient benzene residue limits. Both can meet the safety requirements for oral formulations, with the main process difference lying in the selection of solvent systems. Carbomer 934P adopts an optimized benzene-free solvent system, completely avoiding benzene residue risks from the source. Carbomer 974P uses an ethyl acetate solvent system with lower residual toxicity, making it more preferred in formulation scenarios with high safety requirements.

4. pH Dependence of Drug Release Behavior: Adapting to Different Gastrointestinal Environments

The drug release behavior of both is affected by environmental pH, but their response patterns differ. In the low-pH simulated gastric fluid (SGF) environment, NM-Carbomer 974P showing a faster release rate. When entering the simulated intestinal fluid (SIF) environment with pH≥6, Carbomer 974P undergoes complete hydration of gel particles, further expanding internal channels, significantly increasing the drug release rate, and achieving approximately zero-order release, which is more conducive to the formulation design of controlled-release preparations. In contrast, NM-Carbomer 934P maintains a gentle release trend in the intestinal fluid environment, suitable for formulation scenarios requiring sustained low-dose drug release.

5. Mucoadhesiveness and Synergistic Performance: Expanding the Boundaries of Application Scenarios

With its stronger mucoadhesive capacity, NM-Carbomer 934P has significant advantages in mucosal delivery preparations such as oral patches and sublingual tablets, which can effectively extend the residence time of drugs on the mucosal surface and improve local therapeutic effects. Although NM-Carbomer 974P has slightly weaker mucoadhesiveness, it can be synergistically compounded with thermosensitive polymers such as Poloxamer 407 to prepare in situ gel preparations for nasal, ocular, and other uses.

NM-Carbomer 934P exhibits superior stability in high-viscosity suspension systems, making it more suitable for formulations with strict requirements on suspension uniformity.

III. Application Selection Guide

1.Preferred Application for NM-Carbomer 934P

•         Preparation of long-acting sustained-release formulations (such as sustained-release tablets and capsules) requiring slow drug release in the gastrointestinal environment to extend the duration of action and stabilize blood drug concentration.

•         Design of mucoadhesive preparations for oral, nasal, and other routes, which rely on strong mucoadhesive properties to extend the residence time of drugs on the mucosal surface and improve local bioavailability.

•         Preparation of high-viscosity oral suspensions requiring effective prevention of rapid sedimentation of drug particles to ensure the uniformity and stability of the formulation during its shelf life.

2. Preferred application for NM- Carbomer 974P

•         Preparation of immediate-release or controlled-release formulations (such as orally disintegrating tablets and enteric-coated controlled-release tablets) requiring rapid drug onset or stable zero-order/approximately zero-order release.

•         Formulations for pediatric and elderly populations, or those requiring long-term oral administration, with extremely high requirements on excipient residual toxicity and safety.

•         Preparation of formulations with high requirements on matrix stability after compression, which need the matrix to maintain structural integrity in gastrointestinal fluids to ensure a stable drug release rate.