Chymotrypsin for Ophthalmic Solution
»Chymotrypsin for Ophthalmic Solution is sterile Chymotrypsin.When constituted as directed in the labeling,it yields a solution containing not less than 80.0percent and not more than 120.0percent of the labeled potency.
Packaging and storage— Preserve in single-dose containers,preferably of Type Iglass,and avoid exposure to excessive heat.
Completeness of solution á641ñ— It dissolves in the solvent and in the concentration recommended in the labeling to yield a clear solution.
Identification— Prepare a Substrate solutionas follows.Transfer 237.0mg of N-acetyl-L-tyrosine ethyl ester,suitable for use in assaying chymotrypsin,to a 100-mLvolumetric flask,add 2mLof alcohol,and swirl until solution is effected.Add 20mLof pH7.0phosphate buffer,fifteenth-molar,prepared as directed in the Assayunder Chymotrypsin,add 1mLof methyl red–methylene blue TS,and dilute with water to volume.If necessary,adjust to a pHof 7.0by the dropwise addition of monobasic potassium phosphate solution,prepared by dissolving 4.54g of monobasic potassium phosphate in sufficient water to yield 500mLof solution.Dissolve the contents of 1vial of Chymotrypsin for Ophthalmic Solution in 1mLof saline TS,transfer 0.2mLto a suitable dish,and add 0.2mLof Substrate solution:a purple color is produced within 3minutes.[Note—distinction from trypsin,which produces no purple color within 3minutes.]
Uniformity of dosage units á905ñ: meets the requirements.
Procedure for content uniformity— Assay 10individual units as directed in the Assay,and calculate the average of the 10results.The average is not less than 80.0%and not more than 120.0%of the labeled amount.The contents of not more than 2vials deviate by more than 10%from the average content.The contents of none of the vials deviate by more than 15%from the average.
pHá791ñ: between 4.3and 8.7,in the solution constituted as directed in the labeling.
Other requirements— It meets the requirements of the test for Limit of trypsinunder Chymotrypsin.It also meets the requirements for Sterility Tests á71ñ.
Assay— Proceed with Chymotrypsin for Ophthalmic Solution as directed in the Assayunder Chymotrypsin,but use the following as the Chymotrypsin solution:dissolve the contents of 1vial of Chymotrypsin for Ophthalmic Solution in 5.0mLof 0.0012Nhydrochloric acid.Dilute an accurately measured volume (V,in mL)of this solution,equivalent to about 300USP Chymotrypsin Units,with 0.0012Nhydrochloric acid to 25.0mL.Calculate the number of USP Chymotrypsin Units per vial taken by the formula:
300(5/V)(A2-A1)/[T(2.4)(0.0075)],
in which A2is the absorbance straight-line initial reading,A1is the absorbance straight-line final reading,Tis the elapsed time in minutes between the initial and final readings,and 2.4is the number of USP Chymotrypsin Units in the solution on which the absorbance was determined.
Auxiliary Information— Staff Liaison:Larry N.Callahan,Ph.D.,Scientist
Expert Committee:(BNT)Biotechnology and Natural Therapeutics/Diagnostics
USP28–NF23Page 468
Phone Number:1-301-816-8385