(Ph. Eur. 11.6 update)
Action and use
Vasopressin analogue; treatment of diabetes insipidus.
DEFINITION
Desmopressin Oral Lyophilisate contains Desmopressin with suitable excipients.
The oral lyophilisate complies with the requirements stated under Tablets and with the following requirements.
Content of desmopressin, C46H64N14O12S2
90.0 to 110.0% of the stated amount of the peptide.
IDENTIFICATION
In the Assay, the principal peak in the chromatogram obtained with solution (1) corresponds to that in the chromatogram obtained with solution (2).
TESTS
Related substances
Carry out the method for liquid chromatography, Appendix III D, using the following solutions and the normalisation procedure.
(1) Shake a quantity of the oral lyophilisate with 10 mL of a mixture of 50% of the buffer solution and 50% of water to produce a solution containing 0.0025% w/v of the peptide.
(2) Dissolve the contents of a vial of desmopressin impurity standard BPCRS in 4 mL of a mixture of 50% of the buffer solution and 50% of water.
CHROMATOGRAPHIC CONDITIONS
(a) Use a stainless steel column (15 cm x 3.0 mm) packed with nitrile groups chemically bonded to porous silica particles (5 μm) (Zorbax-SB-CN is suitable).
(b) Use gradient elution and the mobile phase described below.
(c) Use a flow rate of 0.6 mL per minute.
(d) Use a column temperature of 50°.
(e) Use a detection wavelength of 220 nm.
(f) Inject 200 μL of each solution.
Buffer solution
0.05 M ammonium acetate buffer solution, pH 4.6, if necessary adjusted with acetic acid.
Mobile phase A
15 volumes of acetonitrile, 35 volumes of water and 50 volumes of the Buffer solution.
Mobile phase B
15 volumes of water, 40 volumes of acetonitrile and 45 volumes of the Buffer solution.
| Time (Minutes) | Mobile phase A% (% v/v) | Mobile phase B%(% v/v) | Comment |
| 0-16 | 100 | 0 | isocratic |
| 16-31 | 100→0 | 0→100 | linear gragident |
| 31-36 | 0 | 100 | isocratic |
| 36-37 | 0→100 | 0→100 | linear gragident |
| 37-41 | 100 | 100 | re-equilibration |
When the chromatograms are recorded under the prescribed conditions the retention time for the first peak: in solution (2) is about 9 minutes and about 11 minutes for desmopressin.
SYSTEM SUITABILITY
The test is not valid unless:
in the chromatogram obtained with solution (2), the resolution between the two principal peaks is at least 2.0;
the peak due to desmopressin is clearly separated from any peaks due to excipients stated on the label.
LIMITS
In the chromatogram obtained with solution (1):
the area of any secondary peak is not more than 2.0%;
the total area of any such peaks is not more than 4.0%.
Disregard any peak due to the solvent, any excipients stated on the label and any peak with an area less than 0.05%.
ASSAY
Carry out the method for liquid chromatography, Appendix III D, using the following solutions.
(1) Shake a suitable quantity of the oral lyophilisate with 10 mLof a mixture of 50% of the Buffer solution and 50% of water, to give a final concentration of 0.0025% w/v of the peptide.
(2) Dissolve the contents of a vial of desmopressin BPCRS in a mixture of 50% of the Buffer solution and 50% of water to give a final concentration of 0.0025% w/v of the peptide.
(3) Dissolve the contents of a vial of desmopressin impurity standard BPCRS in 4 mL of a mixture of 50% of the Buffer solution and 50% of water.
CHROMATOGRAPHIC CONDITIONS
(a) Use a stainless steel column (15 cm x 3.0 mm) packed with nitrile groups chemically bonded to porous silica particles (5 μm) (Zorbax-SB-CN is suitable).
(b) Use isocratic elution and the mobile phase described below.
(c) Use a flow rate of 0.6 mL per minute.
(d) Use a column temperature of 50°.
(e) Use a detection wavelength of 220 nm.
(f) Inject 200 μL of each solution.
Carry out isocratic elution for at least 16 minutes for each run.
MOBILE PHASE
Buffer solution 0.05M ammonium acetate buffer solution, pH 4.6, 15 volumes of acetonitrile, 35 volumes of water and 50 volumes of the Buffer solution.
SYSTEM SUITABILITY
The test is not valid unless:
in the chromatogram obtained with solution (3), the resolution between the two principal peaks and desmopressin is at least 2.0;
the peak due to desmopressin is clearly separated from any peaks due to excipients stated on the label.
DETERMINATION OF CONTENT
Calculate the content of C46H64N14O12S2 in each tablet from the chromatograms obtained and from the declared content of C46H64N14O12S2 in desmopressin BPCRS.
STORAGE
Desmopressin Oral Lyophilisate should be protected from light and moisture.
IMPURITIES
The impurities limited by the requirements of this monograph include those listed under Desmopressin.
