Sulfamethoxazole and Trimethoprim Tablets
» Sulfamethoxazole and Trimethoprim Tablets contain not less than 93.0 percent and not more than 107.0 percent of the labeled amounts of sulfamethoxazole (C10H11N3O3S) and trimethoprim (C14H18N4O3).
Packaging and storage— Preserve in well-closed, light-resistant containers.
Identification— Transfer an amount of finely ground Tablets, equivalent to 4 mg of trimethoprim, to a 10-mL volumetric flask, add 8 mL of methanol, warm for several minutes on a steam bath with frequent shaking, cool, dilute with methanol to volume, mix, and centrifuge briefly. Apply 5 µL each of this solution, a Standard solution of USP Trimethoprim RS in methanol containing 0.4 mg per mL, and a Standard solution of USP Sulfamethoxazole RS in methanol containing 2 mg per mL to separate points about 3 cm from one end of a thin-layer chromatographic plate coated with chromatographic silica gel mixture. Dry the spots in a current of warm air, and develop the plate with a mixture of chloroform, isopropyl alcohol, and diethylamine (6:5:1) in a chamber lined with filter paper. Remove the plate, dry, and examine under short-wavelength UV light: the trimethoprim and sulfamethoxazole spots from the solution under test have the same RF values as the spots from the corresponding Standard solutions.
Dissolution 711
Medium: 0.1 N hydrochloric acid; 900 mL.
Apparatus 2: 75 rpm.
Time: 60 minutes.
Procedure— Determine the amounts of sulfamethoxazole (C10H11N3O3S) and trimethoprim (C14H18N4O3) dissolved, employing the procedure set forth in the Assay, making any necessary volumetric adjustments (see Chromatography 621). Calculate the percentage of each active component dissolved by comparison of the peak responses obtained from a filtered aliquot of the solution under test with the peak responses from the corresponding component obtained from the Standard preparation.
Tolerances— Not less than 70% (Q) of the labeled amounts of C10H11N3O3S and C14H18N4O3 is dissolved in 60 minutes.
Uniformity of dosage units 905: meet the requirements.
Mobile phase, Standard preparation, and Chromatographic system— Prepare as directed in the Assay under Sulfamethoxazole and Trimethoprim Oral Suspension.
Assay preparation— Weigh and finely powder not fewer than 20 Tablets. Transfer an accurately weighed portion of the powder, equivalent to about 160 mg of sulfamethoxazole, to a 100-mL volumetric flask. Add about 50 mL of methanol and sonicate, with intermittent shaking, for 5 minutes. Allow to equilibrate to room temperature, dilute with methanol to volume, mix, and filter. Transfer 5.0 mL of the clear filtrate to a 50-mL volumetric flask, dilute with Mobile phase to volume, and mix.
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 quantities, in mg, of trimethoprim (C14H18N4O3) and sulfamethoxazole (C10H11N3O3S) in the portion of Tablets taken by the formula:
1000C(rU / rS)
in which C is the concentration, in mg per mL, of the appropriate USP Reference Standard in the Standard preparation; and rU and rS are the responses of the corresponding analyte obtained from the Assay preparation and the Standard preparation, respectively.
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Behnam Davani, Ph.D., M.B.A.
Senior Scientist
(MDAA05) Monograph Development-Antivirals and Antimicrobials
Reference Standards Lili Wang, Technical Services Scientist
711 Margareth R.C. Marques, Ph.D.
Senior Scientist
(BPC05) Biopharmaceutics05
USP32–NF27 Page 3630
Pharmacopeial Forum: Volume No. 29(3) Page 670
Chromatographic Column—
Chromatographic columns text is not derived from, and not part of, USP 32 or NF 27.