Lomustine Capsules

General Notices

Action and use

Cytotoxic alkylating agent.

Definition

Lomustine Capsules contain Lomustine.

The capsules comply with the requirements stated under Capsules and with the following requirements.

Content of lomustine, C9H16ClN3O2

90.0 to 110.0% of the stated amount.

Identification

Carry out the following procedure in subdued light. Shake a quantity of the contents of the capsules containing 0.2 g of Lomustine with 10 mL of methanol, filter and evaporate the filtrate to dryness using a rotary evaporator on a water bath maintained at not more than 60°. The residue, after drying at 60° at a pressure not exceeding 0.7 kPa for 30 minutes, complies with the following tests.

A. The infrared absorption spectrum, Appendix II A, is concordant with the reference spectrum of lomustine (RS 204).
B. Melting point, about 88°, Appendix V A.

TEST

Related substances

A. Carry out the method for thin-layer chromatography, Appendix III A, using the following solutions in methanol.
(1) Shake a quantity of the contents of the capsules containing 0.20 g of Lomustine with 10 mL of methanol and filter.
(2) Dilute 1 volume of solution (1) to 25 volumes and further dilute 1 volume of this solution to 10 volumes.
(3) Dilute 1 volume of solution (2) to 2 volumes.
(4) Dissolve 10 mg of lomustine EPCRS and 10 mg of 1,3-dicyclohexylurea and dilute to 10 mL.
chromatographic conditions
(a) Use as the coating silica gel.
(b) Use the mobile phase as described below.
(c) Apply 5 µL of each solution.
(d) Develop the plate to 15 cm.
(e) After removal of the plate, dry it at 110° for 1 hour. At the bottom of a chromatography tank, place an evaporating dish containing a mixture of 1 volume of 7m hydrochloric acid, 1 volume of water and 2 volumes of a 1.5% w/v solution of potassium permanganate, close the tank and allow to stand for 15 minutes. Place the dried plate in the tank and close the tank. Leave the plate in contact with the chlorine vapour for 5 minutes. Withdraw the plate and place it in a current of cold air until the excess of chlorine is removed and an area of coating below the line of application does not give a blue colour with a drop of potassium iodide and starch solution. Spray with potassium iodide and starch solution.
mobile phase

20 volumes of glacial acetic acid and 80 volumes of toluene.

system suitability

The test is not valid unless the chromatogram obtained with solution (4) shows two clearly separated principal spots.

limits

Any secondary spot in the chromatogram obtained with solution (1) is not more intense than the spot in the chromatogram obtained with solution (2) (0.4%) and not more than one such spot is more intense than the spot in the chromatogram obtained with solution (3) (0.2%).

B. Carry out the method for liquid chromatography, Appendix III D, using the following solutions in methanol.
(1) Shake a quantity of the contents of the capsules containing 0.20 g of Lomustine with 10 mL of methanol and filter.
(2) Dilute 2 volumes of solution (1) to 100 volumes.
chromatographic conditions
(a) Use a stainless steel column (25 cm × 4 mm) packed with end-capped octadecylsilyl silica gel for chromatography (5 to 10 µm) (Nucleosil C18 is suitable).
(b) Use isocratic elution and the mobile phase described below.
(c) Use a flow rate of 2 mL per minute.
(d) Use an ambient column temperature.
(e) Use a detection wavelength of 230 nm.
(f) Inject 20 µL of each solution.
mobile phase

50 volumes of methanol and 50 volumes of water.

When the chromatograms are recorded in the prescribed conditions, the retention time of lomustine is about 25 minutes.

limits

In the chromatogram obtained with solution (1) the sum of the areas of any secondary peaks is not greater than the area of the principal peak in the chromatogram obtained with solution (2) (2%).

Disregard any peak with an area less than 0.05 times the area of the principal peak in the chromatogram obtained with solution (2) (0.1%).

Assay

Carry out the following procedure in subdued light. Shake a quantity of the mixed contents of 20 capsules containing 40 mg of Lomustine with 70 mL of ethanol (96%) for 20 minutes, dilute to 100 mL with the same solvent and filter. Dilute 5 mL of the filtrate to 100 mL with ethanol (96%) and measure the absorbance of the resulting solution at the maximum at 230 nm, Appendix II B. Calculate the content of C9H16ClN3O2 taking 260 as the value of A(1%, 1 cm) at the maximum at 230 nm.