Isosorbide Dinitrate Tablets
» Isosorbide Dinitrate Tablets contain not less than 90.0 percent and not more than 110.0 percent of the labeled amount of C6H8N2O8.
Packaging and storage Preserve in well-closed containers.
USP Reference standards 11
Identification Transfer a suitable quantity of finely powdered Tablets to a glass-stoppered centrifuge tube. Add 10 mL of sodium hydroxide solution (1 in 250), shake to wet the powder, then add 15 mL of solvent hexane, and again shake. Centrifuge the mixture, and transfer the upper phase to a beaker. Evaporate the solvent, and dry the residue in vacuum over anhydrous calcium chloride at room temperature for 16 hours: the IR absorption spectrum of a suitable solution in chloroform of the residue so obtained exhibits maxima only at the same wavelengths as that of a similar preparation from the residue obtained from USP Diluted Isosorbide Dinitrate RS.
Medium: water; 1000 mL.
Apparatus 2: 75 rpm.
Time: 45 minutes.
Mobile phase Prepare a suitable filtered and degassed mixture of pH 3.0, 0.1 M ammonium sulfate and methanol (50:50). Make adjustments if necessary (see System Suitability under Chromatography 621), using sulfuric acid for any necessary pH adjustment.
Chromatographic system (see Chromatography 621) The liquid chromatograph is equipped with a 220-nm detector and a 4.6-mm × 5-cm column that contains packing L1. The flow rate is about 1.0 mL per minute. Chromatograph replicate injections of the Standard solution, and record the peak responses as directed for Procedure: the relative standard deviation is not more than 2.0%, and the tailing factor is not more than 1.5.
Procedure Separately inject equal volumes (about 20 µL) of the Standard solution and a filtered aliquot of the solution under test into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the amount of C6H8N2O8 dissolved in comparison with a Standard solution having a known concentration of USP Diluted Isosorbide Dinitrate RS, similarly prepared and chromatographed.
Tolerances Not less than 70% (Q) of the labeled amount of C6H8N2O8 is dissolved in 45 minutes.
Uniformity of dosage units 905: meet the requirements.
Buffer solution, Mobile phase, Internal standard solution, Standard preparation, and Chromatographic system Prepare as directed in the Assay under Diluted Isosorbide Dinitrate.
Assay preparation Weigh and finely powder not fewer than 20 Tablets. Transfer an accurately weighed portion of the powder, equivalent to about 12.5 mg of isosorbide dinitrate, to a dry, 50-mL volumetric flask, add about 30 mL of Mobile phase, and shake the mixture by hand immediately, to prevent clumping. If clumping persists, disperse with the aid of sonication, or break the aggregates with a stirring rod. Shake for 30 minutes. Add 8.0 mL of Internal standard solution, cool to room temperature, add 8 mL of a 1 in 10 dilution of Buffer solution in water, dilute with Mobile phase to volume, and mix. Pass a portion through a disposable ion-exchange filter.
Procedure Proceed as directed for Procedure in the Assay under Diluted Isosorbide Dinitrate. Calculate the quantity, in mg, of C6H8N2O8 in the portion of Tablets taken by the formula:
50C(RU / RS)in which C is the concentration, in mg per mL, of isosorbide dinitrate from the USP Diluted Isosorbide Dinitrate RS taken for the Standard preparation; and RU and RS are the ratios of the peak responses obtained from the Assay preparation and the Standard preparation, respectively.
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USP35NF30 Page 3588Pharmacopeial Forum: Volume No. 31(5) Page 1375