(Ph. Eur. 11.6 update)
Action and use
Vasopressin analogue; treatment of diabetes insipidus; nocturnal enuresis.
DEFINITION
Desmopressin Tablets contain Desmopressin.
The tablets comply 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 test for Uniformity of content, the principal peak in the chromatogram obtained with solution
(1) corresponds to that in the chromatogram obtained with solution (2).
TESTS
Dissolution
Comply with the dissolution test for tablets and capsules, Appendix XII B1.
TEST CONDITIONS
(a) Use Apparatus 2, rotating the paddle at 75 revolutions per minute.
(b) Use 500 mL of water as the medium.
PROCEDURE
Carry out the method for liquid chromatography, Appendix III D, using the following solutions.
(1) After 45 minutes, withdraw a 20 mL sample of the medium and filter.
(2) Prepare a solution of desmopressin BPCRS in water with a final concentration equal to that expected for solution (1).
CHROMATOGRAPHIC CONDITIONS
The chromatographic procedure described under Uniformity of content may be used.
DETERMINATION OF CONTENT
Calculate the total content of desmopressin C46H64N14O12S2, in the medium using the declared content of C46H64N14O12S2 in desmopressin BPCRS.
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 powdered tablets containing 0.5 mg with 1 mL of water to give a final concentration of 0.05% w/v of the peptide.
(2) Dissolve the contents of a vial of desmopressin impurity standard BPCRS in 0.5 mL of water.
CHROMATOGRAPHIC CONDITIONS
(a) Use a stainless steel column (12 cm x 4.0 mm) packed with octadecylsilyl silica gel for chromatography (5 μm).
(b) Use gradient elution and the mobile phase described below.
(c) Use a flow rate of 1.5 mL per minute.
(d) Use an ambient column temperature.
(e) Use a detection wavelength of 220 nm.
(f) Inject 50 μL of each solution.
MOBILE PHASE
Mobile phase A 0.067M mixed phosphate buffer solution pH 7.0.
Mobile phase B 10 volumes of acetonitrile for chromatography and 10 volumes of mobile phase A.
| Time (Minutes) | Mobile phase A% | Mobile phase B% | Comment |
| 0-4 | 76 | 24 | isocratic |
| 4-18 | 76→58 | 24→42 | linear gragident |
| 18-35 | 58→48 | 42→52 | linear gragident |
| 35-40 | 48→76 | 52→24 | linear gragident |
| 40-50 | 76 | 24 | re-equilibration |
The retention time of desmopressin is about 16 minutes.
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 3.4.
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 or with a relative amount less than 0.05%.
Uniformity of content
Tablets containing less than 2 mg and/or less than 2% w/w of Desmopressin 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) Add sufficient water to one tablet to produce a solution containing 0.01% w/v of Desmopressin.
(2) 0.01% w/v of desmopressin BPCRS in water.
(3) Dissolve the contents of a vial desmopressin impurity standard BPCRSin 0.5 mL of water.
CHROMATOGRAPHIC CONDITIONS
(a) Use a stainless steel column (12 cm x 4.0 mm) packed with octadecylsilyl silica gel for chromatography (5 μm).
(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 220 nm.
(f) Inject 50 μl of each solution.
MOBILE PHASE
2 volumes of acetonitrile for chromatography and 8 volumes of 0.067M mixed phosphate buffer solution pH 7.0.
The retention time of desmopressin is about 5 minutes.
SYSTEM SUITABILITY
The test is not valid unless, in the chromatogram obtained with solution (3), the resolution between the two principal peaks at least 2.8.
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.
ASSAY
Use the average of the individual results determined in the test for Uniformity of content.
STORAGE
Desmopressin Tablets should be protected from moisture.
