Packaging and storage—
Preserve in tight containers.
Labeling—
Label Boluses to indicate that they are for veterinary use only.
Identification—
A:
Crush 1 Bolus, boil a portion of the powder, equivalent to about 300 mg of aspirin, with 50 mL of water, cool, and add a drop of
ferric chloride TS: a violet-red color is produced.
B:
The retention time of the aspirin peak in the chromatogram of the Assay preparation corresponds to that in the chromatogram of the Standard preparation, as obtained in the Assay.
Dissolution 
711
—
Medium:
0.05 M acetate buffer, prepared by mixing 8.97 g of sodium acetate trihydrate with 2700 mL of water, adjusting with glacial acetic acid to a pH of 4.50 ± 0.05, and diluting with water to 3000 mL, and mixing; 500 mL.
Apparatus 1
[NOTE—Use basket and shaft dimensions that accommodate the size of the individual bolus.]: 100 rpm.
Time:
45 minutes.
Diluting solution—
Prepare a mixture of acetonitrile and formic acid (99:1).
Procedure—
Determine the amount of aspirin (C
9H
8O
4) dissolved from UV absorbances at the wavelength of the isosbestic point of aspirin and salicylic acid at 265 ± 2 nm of filtered portions of the solution under test, suitably diluted with
Diluting solution, if necessary, in comparison with a Standard solution having a known concentration of
USP Aspirin RS in the same medium.
[NOTE—Prepare the Standard solution at the time of use.
]
Tolerances—
Not less than 80% (Q) of the labeled amount of C9H8O4 is dissolved in 45 minutes.
Limit of salicylic acid—
Using the chromatograms of the
Standard preparation and the
Assay preparation, obtained as directed in the
Assay, calculate the percentage of salicylic acid (C
7H
6O
3) in the portion of Boluses taken by the formula:
100,000(C / WA)(rU / rS),
in which
C is the concentration, in mg per mL, of
USP Salicylic Acid RS in the
Standard preparation; WA is the quantity, in mg, of aspirin (C
9H
8O
4) in the portion of Boluses taken, as determined in the
Assay; and
rU and
rS are the salicylic acid peak responses obtained from the
Assay preparation and the
Standard preparation, respectively: not more than 0.3% is found.
Assay—
Mobile phase—
Dissolve 2 g of sodium 1-heptanesulfonate in a mixture of 850 mL of water and 150 mL of acetonitrile, and adjust with glacial acetic acid to a pH of 3.4. Make any necessary adjustments (see
System Suitability under
Chromatography 621).
Diluting solution—
Prepare a mixture of acetonitrile and formic acid (99:1).
Assay preparation—
Weigh and finely powder not fewer than 10 Boluses. Transfer an accurately weighed portion of the powder, equivalent to about 400 mg of aspirin, to a 100-mL volumetric flask, dilute with Diluting solution to volume, and stir by mechanical means for about 15 minutes. Pass a portion of this solution through a filter having a 0.5-µm or finer porosity, and use the filtrate as the Assay preparation.
Chromatographic system
(see
Chromatography 621)—The liquid chromatograph is equipped with a 254-nm detector and a 4.6-mm × 25-cm column that contains 5-µm packing L1. The flow rate is about 1 mL per minute. Chromatograph the
Standard preparation, and record the peak responses as directed for
Procedure: the relative retention times are about 0.6 for salicylic acid and 1.0 for aspirin, and the relative standard deviation of the aspirin peak response for replicate injections is not more than 2.0%.
Procedure—
Separately inject equal volumes (about 20 µL) of the
Standard preparation and the
Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity, in mg, of aspirin (C
9H
8O
4) in the portion of Boluses taken by the formula:
1000C(rU / rS),
in which
C is the concentration, in mg per mL, of
USP Aspirin RS in the
Standard preparation; and
rU and
rS are the aspirin peak responses obtained from the
Assay preparation and the
Standard preparation, respectively.
Auxiliary Information—
Staff Liaison :
Ian DeVeau, Ph.D., Associate Director
Expert Committee : (VET05) Veterinary Drugs 05
USP29–NF24 Page 197
Pharmacopeial Forum : Volume No. 31(4) Page 1026
Phone Number : 1-301-816-8178
