Liothyronine Sodium Tablets
» Liothyronine Sodium Tablets contain an amount of C15H11I3NNaO4 equivalent to not less than 90.0 percent and not more than 110.0 percent of the labeled amount of liothyronine (C15H12I3NO4).
Packaging and storage Preserve in tight containers.
USP Reference standards 11
Identification The retention time of the major peak in the chromatogram of the Assay preparation corresponds to the liothyronine peak in the chromatogram of the Standard preparation, as obtained in the Assay.
Dissolution 711 [noteAll containers that are in contact with solutions containing liothyronine sodium are to be made of glass. ]
Medium: pH 10.0 ± 0.05 alkaline borate buffer (see Buffer Solutions in the section Reagents, Indicators, and Solutions); 250 mL.
Apparatus 3: 30 dips per minute, using 20-mesh screen on the top and 40-mesh screen on the bottom of the glass reciprocating cylinder.
Time: 45 minutes.
Determine the amount of liothyronine sodium (C15H12I3NO4) dissolved by employing the following method.
Ammoniated solution Add 0.05 mL of ammonium hydroxide to 200 mL of water.
Mobile phase Prepare a filtered and degassed mixture of water and acetonitrile (55:45) that contains 1 mL of phosphoric acid in each 1000 mL of solution. Make adjustments if necessary (see System Suitability under Chromatography 621).
Standard solution Dissolve an accurately weighed quantity of USP Liothyronine RS in Ammoniated solution, and dilute quantitatively, and stepwise if necessary, with Ammoniated solution to obtain a solution having a known concentration of about 10 µg of USP Liothyronine RS per mL. Dilute a portion of this solution quantitatively, and stepwise if necessary, with water to obtain a solution having a known concentration of about 0.5 µg of USP Liothyronine RS per mL.
Test solution Transfer 20 mL of the solution under test to a centrifuge tube, and centrifuge until a clear supernatant is obtained.
Resolution solution Prepare a solution of USP Liothyronine RS and USP Levothyroxine RS in Ammoniated solution having known concentrations of about 10 µg of each USP Reference Standard per mL. Dilute with water to obtain a concentration of about 0.5 µg of each USP Reference Standard per mL.
Chromatographic system (see Chromatography 621) The liquid chromatograph is equipped with a 225-nm detector and a 4.6-mm × 25-cm column that contains packing L10. The flow rate is about 2 mL per minute. Chromatograph the Resolution solution, and record the peak responses as directed for Procedure: the resolution, R, between liothyronine and levothyroxine is not less than 3.0. Chromatograph the Standard solution, and record the peak responses as directed for Procedure: the relative standard deviation for replicate injections is not more than 4.0%.
Procedure Separately inject equal volumes (about 200 µL) of the Standard solution and the Test solution into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the amount of C15H12I3NO4 dissolved.
Tolerances Not less than 70% (Q) of the labeled amount of C15H12I3NO4 is dissolved in 45 minutes.
Uniformity of dosage units 905: meet the requirements.
Mobile phase, Standard preparation, and Chromatographic system Proceed as directed in the Assay under Liothyronine Sodium.
Assay preparation Weigh and finely powder not fewer than 20 Tablets. Transfer an accurately weighed portion of the powder, equivalent to about 100 µg of liothyronine sodium, to a centrifuge tube, add 2 glass beads, pipet 10 mL of Mobile phase into the tube, and mix using a vortex mixer for 3 minutes. Centrifuge to obtain a clear supernatant, filtering if necessary.
Procedure Proceed as directed in the Assay under Liothyronine Sodium. Calculate the quantity, in µg, of liothyronine (C15H12I3 NO4) in the portion of Tablets taken by the formula:
10C(rU / rS)in which C is the concentration, in µg per mL, of USP Liothyronine RS in the Standard preparation; and rU and rS are the liothyronine peak responses obtained from the Assay preparation and the Standard preparation, respectively.
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USP35NF30 Page 3693Pharmacopeial Forum: Volume No. 34(4) Page 955