» Oxtriphylline Tablets contain an amount of Oxtriphylline equivalent to not less than 90.0 percent and not more than 110.0 percent of the labeled amount of anhydrous theophylline (C7H8N4O2).
Packaging and storage Preserve in tight containers.
Labeling Label Tablets to state both the content of oxtriphylline and the content of anhydrous theophylline.
Identification The chromatogram of the Assay preparation obtained as directed in the Assay exhibits a major peak for theophylline, the retention time of which corresponds to that exhibited in the chromatogram of the Standard preparation obtained as directed in the Assay.
Medium: water; 900 mL.
Apparatus 2: 50 rpm.
Time: 30 minutes.
Procedure Determine the amount of C7H8N4O2 dissolved from UV absorbances at the wavelength of maximum absorbance at about 270 nm of filtered portions of the solution under test, suitably diluted with water, if necessary, in comparison with a Standard solution having a known concentration of USP Oxtriphylline RS in the same medium.
Tolerances Not less than 80% (Q) of the labeled amount of C7H8N4O2 is dissolved in 30 minutes.
Uniformity of dosage units 905: meet the requirements.
Mobile phase Dissolve 6.8 g of monobasic potassium phosphate in water to make 1000 mL, and adjust with 0.1 N potassium hydroxide to a pH of 5.8 ± 0.1. Prepare a filtered and degassed mixture of this solution and methanol (4:1). Make adjustments if necessary (see System Suitability under Chromatography 621).
System suitability preparation Dissolve suitable quantities of USP Oxtriphylline RS and theobromine in water to obtain a solution containing about 0.6 mg and 0.3 mg per mL, respectively. Dilute this solution quantitatively, and stepwise if necessary, with water to obtain a solution containing about 60 µg of USP Oxtriphylline RS per mL and about 30 µg of theobromine per mL.
Standard preparation Dissolve an accurately weighed quantity of USP Oxtriphylline RS in water, and dilute quantitatively, and stepwise if necessary, with water to obtain a solution having a known concentration of about 0.1 mg per mL.
Assay preparation Place 10 Tablets in a 1000-mL volumetric flask, and add about 700 mL of water. Heat on a steam bath, with occasional shaking, until the Tablets have disintegrated. Cool to room temperature, dilute with water to volume, mix, and filter. Transfer an accurately measured volume of this solution, equivalent to about 20 mg of Oxtriphylline, to a 200-mL volumetric flask, dilute with water to volume, and mix.
Chromatographic system (see Chromatography 621)The liquid chromatograph is equipped with a 275-nm detector and a 3.9-mm × 30-cm column that contains packing L1. The flow rate is about 1 mL per minute. Chromatograph the System suitability preparation, and record the peak responses as directed for Procedure: the relative retention times are about 0.7 for theobromine and 1.0 for theophylline, and the resolution, R, between the theobromine and theophylline peaks is not less than 3.0. Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the relative standard deviation for replicate injections is not more than 2.0%.
Procedure Separately inject equal volumes (about 10 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. [noteThe major peaks recorded in the chromatograms represent the theophylline moiety of oxtriphylline.] Calculate the quantity, in mg, of C7H8N4O2 in the portion of Tablets taken by the formula:
(180.17 / 283.33)(20C / V)(rU / rS)in which 180.17 and 283.33 are the molecular weights of anhydrous theophylline and oxtriphylline, respectively; C is the concentration, in µg per mL, of USP Oxtriphylline RS in the Standard preparation; V is the volume, in mL, of solution taken for the Assay preparation; and rU and rS are the theophylline peak responses obtained from the Assay preparation and the Standard preparation, respectively.
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USP32NF27 Page 3158
Chromatographic columns text is not derived from, and not part of, USP 32 or NF 27.