Liothyronine Tablets

General Notices

Action and use

Thyroid hormone replacement.

Definition

Liothyronine Tablets contain Liothyronine Sodium.

The tablets comply with the requirements stated under Tablets and with the following requirements.

Content of liothyronine sodium, C15H11I3NNaO4

90.0 to 110.0% of the stated amount.

Identification

In the Assay, the retention time of the principal peak in the chromatogram obtained with solution (1) is the same as that of the peak in the chromatogram obtained with solution (2).

Test

Uniformity of content

Tablets containing less than 2 mg and/or less than 2% w/w of Liothyronine comply with the requirements stated under Tablets using the following method of analysis. Carry out the method for liquid chromatography, Appendix III D, using the following solutions in 0.05m sodium hydroxide.

(1) Add sufficient 0.05m sodium hydroxide to one tablet to produce a solution containing about 6 µg per mL of Liothyronine Sodium, mix with the aid of ultrasound until the tablet is fully dispersed, cool and shake for 2 minutes. Add sufficient 0.05m sodium hydroxide to produce a solution containing 0.0004% w/v of Liothryonine Sodium, filter through glass microfibre filter paper (Whatman GF/C is suitable) and use the filtrate.
(2) 0.0004% w/v of liothyronine sodium EPCRS.
chromatographic conditions
(a) Use a stainless steel column (25 cm × 4.6 mm) packed with nitrile silica gel for chromatography (5 µm) (Nucleosil 5 CN is suitable).
(b) Use isocratic elution and the mobile phase described below.
(c) Use a flow rate of 1 mL per minute.
(d) Use an ambient column temperature.
(e) Use a detection wavelength of 225 nm.
(f) Inject 20 µL of each solution.
mobile phase

5 volumes of orthophosphoric acid, 300 volumes of acetonitrile and 700 volumes of water.

determination of content

Calculate the content of C15H11I3NNaO4 in each tablet using the declared content of C15H11I3NNaO4 in liothyronine sodium EPCRS.

Assay

Weigh and powder 20 tablets. Carry out the method for liquid chromatography, Appendix III D, using the following solutions in equal volumes of methanol and 0.1m sodium hydroxide (solvent A).

(1) Disperse with the aid of ultrasound for 10 minutes a quantity of the powdered tablets containing 0.1 mg of Liothyronine Sodium with 8 mL of solvent A. Shake for 2 minutes, cool, add sufficient solvent A to produce 10 mL, mix, filter through glass microfibre filter paper (Whatman GF/C is suitable) and use the filtrate.
(2) 0.001% w/v of liothyronine sodium EPCRS.
(3) 0.0005% w/v of liothyronine sodium EPCRS and 0.0005% w/v of levothyroxine sodium BPCRS.
chromatographic conditions

The chromatographic conditions described under Uniformity of content may be used.

system suitability

The Assay is not valid unless the resolution factor between the two principal peaks in the chromatogram obtained with solution (3) is at least 4.0.

determination of content

Calculate the content of C15H11I3NNaO4 in the tablets using peak areas and the declared content of C15H11I3NNaO4 in liothyronine sodium EPCRS.

Storage

Liothyronine Tablets should be protected from light.