Table 4.
Chemical composition and properties of selected polycarbophil and Carbopol varieties.
| Trade Name/Variety | United States (USP/NF) (a) (after 1 January 2006) | Viscosity, cP (b) (0.5 wt% at pH 7.5) |
Molecular Weight between Adjacent Cross-Links [92] | Molecular Weight, Da [92,97] | Crosslinker Type (b) | Use (b) | Residual Solvent (b) | Others (b) |
|---|---|---|---|---|---|---|---|---|
| Carbopol® 971P | Carbomer Homopolymer Type A (c) | 4000–11,000 | 237,600 Lightly cross-linked |
1.25 × 106 | Allyl ethers of sucrose or pentaerythritol | Oral and topical | Ethylacetate (<0.5%) | More efficient in controlling drug release than Carbopol® 974P |
| Carbopol® 71G | Carbomer Homopolymer Type A (c) | 4000–11,000 | 237,600 Lightly cross-linked |
1.25 × 106 | Allyl ethers of sucrose or pentaerythritol | Oral and topical | Ethylacetate (<0.5%) | Free-flowing granular form of Carbopol 971P NF |
| Carbopol® 974P | Carbomer Homopolymer Type B (d) | 29,400–39,400 | 104,400 Densely cross-linked |
3 × 106 | Allyl ethers of sucrose or pentaerythritol | Oral and topical | Ethylacetate (<0.5%) | Highly crosslinked polymer |
| Carbopol® 934 | Carbomer Homopolymer Type B (d) | 30,500–39,400 | 104,400 Densely cross-linked |
3 × 106 | Allyl ethers of sucrose or pentaerythritol | Topical | Benzene (<0.2%) | (e) Carbopol® 5984 EP and Ultrez 10 NF polymers |
| Carbopol® 934P | Carbomer Homopolymer Type B (d) | 29,400–39,400 | 104,400 Lightly cross-linked |
3 × 106 | Allyl ethers of sucrose or pentaerythritol | Topical or Oral | Benzene (<100 ppb) |
High purity grade of Carbopol® 934 (e) Carbopol® 974P |
| Noveon® AA-1 |
Polycarbophil | 2000–12,000 | Lightly cross-linked | 7 × 105 [97] | Divinyl glycol | Topical or Oral | Ethyl acetate (<0.45%) |
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Carboxylic acid content for Carbopol (Assay %): 56.0–68.0%. the pKa of the carbopols and polycarbophils was reported to be 6.0 (±0.5) [63]. The Carbomers Monograph in the European Pharmacopeia stipulates that benzene is limited to 2 ppm. (a) UPS-NF: Combination of two compendia, the United States Pharmacopeia (USP) and the National Formulary (NF) (https://www.uspnf.com/; accessed in May 2020). (b) https://www.lubrizol.com/Health/Pharmaceuticals/Excipients/Carbopol-Polymer-Products (Accessed in April 2020). (c) Carbomer Homopolymer Type A: Viscosity Specified (cP): 4000–11,000. (d) Carbomer Homopolymer Type B: Viscosity Specified (cP): 25,000–45,000. (e) Recommended non-benzene substitute products.