Edition: BP 2025 (Ph. Eur. 11.6 update)
Action and use
Beta2-adrenoceptor agonist; bronchodilator.
DEFINITION
Clenbuterol Oral Solution contains Clenbuterol Hydrochloride in a suitable vehicle.
The Oral Solution complies with the requirements stated under Oral Liquids and with the following requirements.
Content of clenbuterol hydrochloride, C12H18Cl2N2O,HCl
95.0 to 105.0% of the stated amount.
IDENTIFICATION
In the Assay, record the UV spectrum of the principal peak in the chromatograms obtained with solutions (1) and (2) with a diode array detector in the range of 200 to 400 nm:
the UV spectrum of the principal peak in the chromatogram obtained with solution (1) is similar to that of the peak in the chromatogram obtained with solution (2);
the retention time of the principal peak in the chromatogram obtained with solution (1) is similar to that of the peak in the chromatogram obtained with solution (2).
TESTS
Related substances
Carry out the method for liquid chromatography, Appendix III D, using the following solutions.
Solution A 2 volumes of acetonitrile, 2 volumes of methanol and 6 volumes of water.
(1) To a volume of the oral solution containing 0.375 mg of Clenbuterol Hydrochloride, add 2 g of sodium chloride and shake for 15 minutes. Dilute to 25 mL with solution A, mix and filter (a 0.45-µm PTFE filter is suitable), discarding the first 3 mL of filtrate.
(2) Dilute 1 volume of solution (1) to 100 volumes with solution A.
(3) 0.0015% w/v of clenbuterol hydrochloride BPCRS and 0.000015% w/v each of clenbuterol impurity B EPCRS and clenbuterol impurity D BPCRS in solution A.
(4) Dilute 1 volume of solution (2) to 10 volumes with solution A.
CHROMATOGRAPHIC CONDITIONS
(a) Use a stainless steel column (25 cm × 4.6 mm) packed with end-capped octadecylsilyl amorphous organosilica polymer (5 µm) (XTerra MS C18 is suitable).
(b) Use gradient elution and the mobile phase described below.
(c) Use a flow rate of 1 mL per minute.
(d) Use an ambient temperature.
(e) Use a detection wavelength of 300 nm.
(f) Inject 100 µL of each solution.
MOBILE PHASE
Mobile phase A 0.05M sodium hexanesulfonate in water.
Mobile phase B methanol.
Mobile phase C acetonitrile.
| Time (Minutes) | Mobile phase A (% v/v) | Mobile phase B (% v/v) | Mobile phase C (% v/v) | Comment |
| 0-10 | 80 | 15 | 5 | isocratic |
| 10-15 | 80 | 15→0 | 5→20 | linear gradient |
| 15-33 | 80→50 | 0 | 20→50 | linear gradient |
| 33-34 | 50→5 | 0 | 50→95 | linear gradient |
| 34-44 | 5 | 0 | 95 | isocratic |
| 44-45 | 5→80 | 0→15 | 95→5 | linear gradient |
| 45-50 | 89 | 15 | 5 | re-equilibration |
When chromatograms are recorded under the prescribed conditions, the relative retentions with reference to clenbuterol (retention time about 8 minutes) are: impurity D, about 0.3; impurity A; about 0.5 and impurity B, about 1.3.
SYSTEM SUITABILITY
The test is not valid unless, in the chromatogram obtained with solution (3), the resolution between the peaks due to impurity B and clenbuterol is at least 1.5.
LIMITS
Identify any peaks corresponding to impurities A, B and D in the chromatogram obtained with solution (1), using the chromatogram obtained with solution (3) and the relative retentions, and multiply the peak areas by the following correction factors: impurity D, 0.1; impurity A, 0.1 and impurity B, 0.2.
In the chromatogram obtained with solution (1):
the area of any secondary peak is not greater than the area of the principal peak in the chromatogram obtained with solution (2) (1%);
the sum of the areas of any secondary peaks is not greater than 2.5 times the area of the principal peak in the chromatogram obtained with solution (2) (2.5%).
Disregard any peak with an area less than 3 times the area of the principal peak in the chromatogram obtained with solution (4) (0.3%).
ASSAY
Carry out the method for liquid chromatography, Appendix III D, using the following solutions.
Solution A 2 volumes of acetonitrile, 2 volumes of methanol and 6 volumes of water.
(1) To a weighed quantity of the oral solution containing 0.375 mg of Clenbuterol Hydrochloride, add 2 g of sodium chloride and shake for 15 minutes. Dilute to 25 mL with solution A, mix and filter (a 0.45-µm PTFE filter is suitable), discarding the first 3 mL of filtrate.
(2) 0.0015% w/v of clenbuterol hydrochloride BPCRS in solution A.
(3) 0.0015% w/v of clenbuterol hydrochloride BPCRS and 0.000015% w/v of clenbuterol impurity B EPCRS in solution A.
CHROMATOGRAPHIC CONDITIONS
The chromatographic conditions described under Related Substances may be used with a detection wavelength of 211 nm.
SYSTEM SUITABILITY
The Assay is not valid unless, in the chromatogram obtained with solution (3), the resolution between the peaks due to impurity B and clenbuterol is at least 1.5.
DETERMINATION OF CONTENT
Determine the weight per mL of the oral solution, Appendix V G, and calculate the content of C12H18Cl2N2O,HCl, weight in volume, using the declared content of C12H18Cl2N2O,HCl in clenbuterol hydrochloride BPCRS.
STORAGE
Clenbuterol Oral Solution should be protected from light.
IMPURITIES
The impurities limited by the requirements of this monograph include impurities A, B and D listed under Clenbuterol Hydrochloride.
