Colistin and Neomycin Sulfates and Hydrocortisone Acetate Otic Suspension
»Colistin and Neomycin Sulfates and Hydrocortisone Acetate Otic Suspension is a sterile suspension containing the equivalent of not less than 90.0percent and not more than 135.0percent of the labeled amount of colistin,not less than 90.0percent and not more than 125.0percent of the labeled amount of neomycin,and not less than 90.0percent and not more than 110.0percent of the labeled amount of hydrocortisone acetate (C23H32O6).It contains one or more suitable buffers,detergents,dispersants,and preservatives.
NOTE—Where Colistin and Neomycin Sulfates and Hydrocortisone Acetate Otic Suspension is prescribed,without reference to the quantity of colistin,neomycin,or hydrocortisone acetate contained therein,a product containing 3.0mg of colistin,3.3mg of neomycin,and 10mg of hydrocortisone acetate per mLshall be dispensed.
Packaging and storage— Preserve in tight containers.
Sterility á71ñ: meets the requirements,0.25mLfrom each container being transferred directly to 90mLof each medium.
pHá791ñ: between 4.8and 5.2.
Assay for colistin— Proceed as directed under Antibiotics—Microbial Assays á81ñ,using a freshly mixed,accurately measured volume of Otic Suspension diluted quantitatively and stepwise with Buffer No.6to yield a Test Dilutionhaving a concentration assumed to be equal to the median dose level of the Standard.
Assay for neomycin— Proceed as directed under Antibiotics—Microbial Assays á81ñ,using a freshly mixed,accurately measured volume of Otic Suspension diluted quantitatively and stepwise with Buffer No.3to yield a Test Dilutionhaving a concentration assumed to be equal to the median dose level of the Standard.
Assay for hydrocortisone acetate—
Reagent blank— Dilute 200mLof 22Nsulfuric acid with 100mLof dehydrated alcohol.
Phenylhydrazine reagent— Dissolve 43.33mg of phenylhydrazine hydrochloride in 100mLof Reagent blank.
Standard preparation— Dissolve a suitable quantity of USP Hydrocortisone Acetate RS,accurately weighed,in chloroform,and dilute quantitatively and stepwise with chloroform to obtain a solution having a known concentration of about 10µg per mL.
Assay preparation— Transfer 5.0mLof freshly mixed Otic Suspension to a 125-mLseparator.Extract with three 20-mLportions of chloroform,filtering each chloroform extract through a pledget of cotton previously saturated with chloroform,collect the filtrates in a 100-mLvolumetric flask,dilute with chloroform to volume,and mix.Pipet 10mLof this solution into a 100-mLvolumetric flask,dilute with chloroform to volume,and mix.Pipet 20mLof this solution into a 100-mLvolumetric flask,dilute with chloroform to volume,and mix.
Procedure— Pipet 50mLeach of the Standard and the Assay preparationinto separate 125-mLseparators,add 2mLof 0.1Nsodium hydroxide to each separator,shake,and allow the layers to separate.Filter both chloroform layers through glass wool,and collect the filtrates in separate beakers.Pipet two 20-mLportions of each chloroform filtrate into separate 125-mLseparators.Add 25.0mLof Phenylhydrazine reagentto one separator each of the filtrates from the Standard preparationand the Assay preparation,respectively,and add 25.0mLof Reagent blankto the remaining two separators.Shake all four separators well,allow the layers to separate,and discard the chloroform layers.Drain the aqueous layers into separate centrifuge tubes,and centrifuge for 2minutes.Pipet 10mLof each solution into separate glass-stoppered test tubes.Place the tubes in a water bath maintained at a temperature of 60for 30minutes,then cool the solution to room temperature.Concomitantly determine the absorbances of the solutions at the wavelength of maximum absorbance at about 410nm,with a suitable spectrophotometer,using water to set the instrument.Calculate the quantity,in mg,of hydrocortisone acetate (C23H32O6)in each mLof the Otic Suspension taken by the formula:
C(AU-AUB/AS-ASB),
in which Cis the concentration,in µg per mL,of USP Hydrocortisone Acetate RSin the Standard preparation;AUand ASare the absorbances of the solutions from the Assay preparationand the Standard preparationtreated with Phenylhydrazine reagent,respectively;and AUBand ASBare the absorbances of the solution from the Assay preparationand the Standard preparationtreated with the Reagent blank,respectively.
Auxiliary Information— Staff Liaison:William W.Wright,Ph.D.,Scientific Fellow
Expert Committee:(PA7)Pharmaceutical Analysis 7
USP28–NF23Page 542
Phone Number:1-301-816-8335