Edition: BP 2025 (Ph. Eur. 11.6 update)
Dexamethasone Tablets
General Notices
Action and use
Glucocorticoid.
DEFINITION
Dexamethasone Tablets contain Dexamethasone.
The tablets comply with the requirements stated under Tablets and with the following requirements.
Content of dexamethasone, C22H29FO5
95.0 to 105.0% of the stated amount.
Carry out all of the following procedures protected from light.
IDENTIFICATION
Mix a quantity of the powdered tablets containing 20 mg of Dexamethasone with 5 mL of 0.1M sodium hydroxide, add 50 mL of dichloromethane and mix with the aid of ultrasound for 20 minutes, filter and evaporate to dryness using a rotary evaporator. Dry the residue at 105° for 2 hours. The infrared absorption spectrum of the dried residue, Appendix II A, is concordant with the reference spectrum of dexamethasone (RS 089).
TESTS
Related substances
Carry out the method for liquid chromatography, Appendix III D, using the following solutions.
(1) To a quantity of the powdered tablets containing 2.5 mg of Dexamethasone add 10 mL of acetonitrile, mix with the aid of ultrasound and filter through a 0.45-µm filter. Dilute 4 mL of the filtrate to 10 mL with water. (2) Dilute 1 volume of solution (1) to 100 volume with mobile phase A.
(3) 0.002% w/v each of dexamethasone BPCRS and methylprednisolone BPCRS in mobile phase A. (4) Dilute 1 volume of solution (2) to 20 volumes with mobile phase A.
CHROMATOGRAPHIC CONDITIONS
(a) Use a stainless steel column (25 cm × 4.6 mm) packed with octadecylsilyl silica gel for chromatography (5 µm) (Hypersil ODS is suitable).
(b) Use gradient elution and the mobile phases described below.
(c) Use a flow rate of 2.5 mL per minute.
(d) Use a column temperature of 45°.
(e) Use a detection wavelength of 254 nm.
(f) Inject 20 µL of each solution.
(g) The retention times are: methylprednisolone about 13 min and dexamethasone about 16 min.
MOBILE PHASE
Mobile phase A 15% v/v acetonitrile.
Mobile phase B acetonitrile.
| Time (min) | Mobile phase A (% v/v) | Mobile phase B (% v/v) | Comments |
|---|---|---|---|
| 0 | 100 | 0 | isocratic |
| 15 | 100 → 0 | 0 → 100 | begin linear gradient |
| 40 | 0 | 100 | end chromatogram, return to 100 A |
| 41 | 100 | 0 | begin equilibration with A |
| 46 = 0 | 100 | 0 | end equilibration, begin next chromatogram |
SYSTEM SUITABILITY
The test is not valid unless, in the chromatogram obtained with solution (3), the resolution factor between methylprednisolone and dexamethasone is at least 2.8.
LIMITS
In the chromatogram obtained with solution (1):
the area of any secondary peak is not greater than 0.5 times the area of the principal peak in the chromatogram obtained with solution (2) (0.5%);
the sum of the areas of all the secondary peaks is not greater than the area of the principal peak in the chromatogram obtained with solution (2) (1.0%).
Disregard any peak due to mobile phase A and any peak with an area less than the area of the principal peak in the chromatogram obtained with reference solution (4) (0.05%).
Uniformity of content
Tablets containing less than 2 mg and or less than 2% w/w of Dexamethasone 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.
(1) To one tablet, add sufficient methanol (50%) to produce a solution containing 0.0025% w/v of Dexamethasone, shake for 10 minutes and filter through glass-fibre filter (Whatman GF/C is suitable).
(2) 0.0025% w/v of dexamethasone BPCRS in methanol (50%).
CHROMATOGRAPHIC CONDITIONS
(a) Use a stainless steel column (20 cm × 4.6 mm) packed with octadecylsilyl silica gel for chromatography (5 µm) (Spherisorb ODS 1 is suitable).
(b) Use isocratic elution and the mobile phase described below.
(c) Use a flow rate of 1.4 mL per minute.
(d) Use an ambient column temperature.
(e) Use a detection wavelength of 238 nm.
(f) Inject 20 µL of each solution.
MOBILE PHASE
47 volumes of methanol and 53 volumes of water.
DETERMINATION OF CONTENT
Calculate the content of C22H29FO5 in each tablet using the declared content of C22H29FO5 in dexamethasone BPCRS.
ASSAY
For tablets containing less than 2 mg and/or less than 2% w/w of Dexamethasone
Use the average of the individual results determined in the test for Uniformity of content.
For tablets containing 2 mg or more and 2% w/w of Dexamethasone
Weigh and powder 20 tablets. Carry out the method for liquid chromatography, Appendix III D, using the following solutions.
(1) To a quantity of the powdered tablets containing 2.5 mg of Dexamethasone add 20 mL of methanol (50%), shake for 20 minutes and filter through glass-fibre filter (Whatman GF/C is suitable).
(2) 0.0125% w/v of dexamethasone BPCRS in methanol (50%).
CHROMATOGRAPHIC CONDITIONS
The chromatographic conditions described under Uniformity of content may be used.
DETERMINATION OF CONTENT
Calculate the content of C22H29FO5 in the tablets using the declared content of C22H29FO5 in dexamethasone BPCRS.
STORAGE
Dexamethasone Tablets should be protected from light.
