Hypromellose Ophthalmic Solution
» Hypromellose Ophthalmic Solution is a sterile solution of Hypromellose. It contains not less than 85.0 percent and not more than 115.0 percent of the labeled amount of Hypromellose (hydroxypropyl methylcellulose). It may contain suitable antimicrobial, buffering, and stabilizing agents.
Packaging and storage— Preserve in tight containers.
USP Reference standards 11
USP Hypromellose RS Click to View Structure
A: Pour a few mL of Ophthalmic Solution onto a glass plate, and allow the water to evaporate: a thin, self-sustaining film results.
B: Heat 5 mL of Ophthalmic Solution in a test tube over a low flame: the warm solution turns cloudy but clears upon chilling.
Sterility 71: meets the requirements.
pH 791: between 6.0 and 7.8.
Standard preparation— Dissolve a suitable quantity of USP Hypromellose RS, accurately weighed, in water, and dilute quantitatively with water to obtain a solution having a known concentration of about 100 µg per mL.
Assay preparation— Dilute an accurately measured volume of Ophthalmic Solution quantitatively with water to obtain a solution having an equivalent concentration of about 100 µg of hypromellose per mL.
Procedure— Pipet 2 mL each of the Standard preparation, the Assay preparation, and water to provide a blank, into separate, glass-stoppered test tubes. To each tube add 5.0 mL of diphenylamine solution (prepared by dissolving 3.75 g of colorless diphenylamine crystals in 150 mL of glacial acetic acid and diluting the solution with 90 mL of hydrochloric acid), mix, and immediately insert the tubes into an oil bath at 105 to 110 for 30 minutes, the temperature being kept uniform within 0.1 during heating. Remove the tubes, and place them in an ice-water bath for 10 minutes or until thoroughly cool. At room temperature and using a suitable spectrophotometer, concomitantly determine the absorbances of the solutions from the Standard preparation and the Assay preparation at 635 nm, using the water solution as the blank. Calculate the quantity, in mg, of hypromellose in each mL of the Ophthalmic Solution taken by the formula:
0.001Cd(AU / AS)
in which C is the concentration, in µg per mL, of USP Hypromellose RS in the Standard preparation; d is the dilution factor used to obtain the Assay preparation; and AU and AS are the absorbances of the solutions from the Assay preparation and the Standard preparation, respectively.
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