Carbomer Interpolymer
»Carbomer Interpolymer is a carbomer homopolymer or copolymer that contains a block copolymer of polyethylene glycol and a long chain alkyl acid ester.
NOTE—Different types of Carbomer Interpolymers may not have identical properties with respect to their use for specific pharmaceutical purposes,e.g.,as tablet controlled-release agents,bioadhesives,topical gels,thickening agents,and emulsifying agents.Therefore,different types of Carbomer Interpolymers should not be interchanged unless performance equivalency has been ascertained.
Packaging and storage— Preserve in tight containers,at a temperature not exceeding 45.
Labeling— Label it to indicate the nominal viscosity range and the measured viscosity,the solvent or solvents used in the polymerization process,and the nominal and measured residual solvent levels for each solvent.
Identification—
A:Infrared Absorption á197Kñ— The IRabsorption spectrum exhibits bands at or near (±5)wave numbers (cm-1)1710,1454,1414,1245,1172,1115,and 801,with the strongest band at 1710.
B: Without mixing,add 2.5g of Carbomer Interpolymer to 500mLof water in an 800-mLbeaker,and allow to stand.The powders wet out in not more than 60minutes.
C: Add about 5g of Carbomer Interpolymer to 500mLof water,stir,and adjust with 1Nsodium hydroxide to a pHof about 7.5.It forms a viscous gel.
Viscosity á911ñ—
Carbomer Interpolymer A— Proceed as directed forViscosity underCarbomer Copolymer,except to perform the test on a 0.5%aqueous dispersion prepared by using 2.50g instead of 5.00g of copolymer.
Carbomer Interpolymer B— Proceed as directed forViscosity underCarbomer Copolymer,except to adjust the pHof the dispersion to within the range of 5.8to 6.3instead of 7.3to 7.8.
Carbomer Interpolymer C— Proceed as directed for Viscosityunder Carbomer Copolymer,except to perform the test on a 0.5%aqueous dispersion prepared by using 2.50g instead of 5.00g of copolymer and adjust the pHof the dispersion to within the range of 5.8and 6.3instead of 7.3to 7.8.The viscosity values,determined by the conditions specified herein,are within the limits specified in the accompanying table.
Carbomer Interpolymer Viscosity Specifications,in cP
A 45,000–65,000
B 47,000–77,000
C 8,500–16,500
Loss on drying á731ñ— Dry it in vacuum at 80for 1hour:it loses not more than 2.0%of its weight.
Limit of ethyl acetate and cyclohexane— [NOTE—This test is required only for those Carbomer Interpolymers where the labeling indicates that ethyl acetate or a mixture of ethyl acetate and cyclohexane was used in the polymerization process.]
Standard stock solution— Proceed as directed in the test forLimit of ethyl acetate and cyclohexane underCarbomer Copolymer,except to use 20µLof ethyl acetate and 10µLof cyclohexane.
Standard solution— Proceed as directed in the test forLimit of ethyl acetate and cyclohexane underCarbomer Copolymerto obtain a solution containing 0.18mg of ethyl acetate and 0.078mg of cyclohexane.
Test solutionand Chromatographic system— Proceed as directed in the test forLimit of ethyl acetate and cyclohexane underCarbomer Copolymer.
Procedure— Proceed as directed in the test forLimit of ethyl acetate and cyclohexane underCarbomer Copolymer,except to calculate the percentages of ethyl acetate and cyclohexane in the portion of Carbomer Interpolymer taken by the formula:
100(WS/WT)(RU/RS),
in whichWTis the weight,in mg,of Carbomer Interpolymer taken to prepare theTest solution;and the other terms are as defined therein:not more than 0.35%of ethyl acetate and not more than 0.15%of cyclohexane is found.
Limit of acrylic acid—
pH3.0Phosphate buffer,Mobile phase,Standard solution,Test solution,and Chromatographic system— Proceed as directed in the test forLimit of acrylic acid underCarbomer Copolymer.
Procedure— Proceed as directed in the test forLimit of acrylic acid underCarbomer Copolymer,except to calculate the percentage of free acrylic acid in the portion of Carbomer Interpolymer taken by the formula:
(C/W)(rU/rS),
in whichWis the weight,in mg,of Carbomer Interpolymer taken to prepare theTest solution;and the other terms are as defined therein:not more than 0.25%is found.
Content of carboxylic acid— Proceed as directed in the test forContent of carboxylic acid underCarbomer Copolymer,except to calculate the percentage of carboxylic acid in the portion of Carbomer Interpolymer taken by the formula:
100(45.02VN/W),
in whichWis the weight,in mg,of the portion of Carbomer Interpolymer taken;and the other terms are as defined therein.The carboxylic acid content is not less than 52.0%and not more than 62.0%.
Auxiliary Information— Staff Liaison:Catherine Sheehan,B.Sc.,Scientist
Expert Committee:(EMC)Excipients:Monograph Content
USP28–NF23Page 2976
Pharmacopeial Forum:Volume No.29(3)Page 692
Phone Number:1-301-816-8262