Vasopressin

This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition

Issued and maintained by the United States Pharmacopeial Convention (USP)

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C₄₆H₆₅N₁₅O₁₂S₂              1084.24

Vasopressin, 8-L-arginine CAS RN^®: 113-79-1; UNII: Y490706MFD.

1 DEFINITION

Vasopressin is a polypeptide hormone having the properties of causing the contraction of vascular and other smooth muscles, and of antidiuresis. It is prepared by chemical synthesis. It contains NLT 95.0% and NMT 105.0% of vasopressin (C₄₆H₆₅N₁₅O₁₂S₂), calculated on the anhydrous, acetic acid-free basis.

2 IDENTIFICATION

2.1 A.

The retention time of the vasopressin peak of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay.

2.2 B. MASS SPECTRAL ANALYSIS

Infusion solution: Acetonitrile, water, and trifluoroacetic acid (80:20:0.08)

Standard solution: 1 mg/ml. of USP Vasopressin RS in water

Sample solution: 1 mg/mL of Vasopressin in water.

[ NOTE-The final concentrations of the Standard solution and the Sample solution can be adjusted, depending on the sensitivity of the mass spectrometer used in the testing.]

Instrumental conditions

(See Mass Spectrometry (736).)

Mode: LC/MS spectrometer

Interface/detection: Infusion system connected to an electrospray interface (positive ion)

Flow rate: 0.3 mL/min

Injection size: 10 µL

Analysis

Samples: Standard solution and Sample solution

Acceptance criteria: Should contain peaks with mass-to-charge ratios of 1084 and 543

3 ASSAY

PROCEDURE

Mobile phase: Dissolve 6.6 g of dibasic ammonium phosphate in 950 mL of water. Adjust with concentrated phosphoric acid to a pH of 3.0. Dilute with water to 1000 mL. To 870 mL of this solution add 130 ml. of acetonitrile, and mix. Filter under vacuum through a nylon membrane of 0.45-µm pore size. [NOTE-The retention time of the vasopressin peak is very sensitive to small changes in acetonitrile concentration in the Mobile phase.]

System suitability solution: Dissolve suitable quantities of USP Lypressin RS and USP Vasopressin RS in 0.25% glacial acetic acid to obtain a solution having a known concentration of about 25 µg/mL of each substance.

Standard solution: Dissolve the entire contents of a vial of USP Vasopressin RS in a known volume of 0.25% glacial acetic acid. [NOTE-The solution may be diluted as necessary to a working concentration range for the Assay.]

Sample solution: Transfer about 10 mg of Vasopressin to a 25-mL volumetric flask. Dissolve in 0.25% glacial acetic acid, and dilute with the same solvent to volume.

Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: LC

Detector: UV 220 nm

Column: 4.6-mm x 25-cm; packing L1

Column temperature: 40 ± 1°

Flow rate: 1.0 mL/min

Injection size: 20 µL. [NOTE-The column is allowed to equilibrate for 1 h before making the first injection.]

System suitability

Samples: System suitability solution and Standard solution. [NOTE-Inject into an equilibrated liquid chromatograph, allowing about 60 min for complete elution.]

[NOTE-The retention time of the vasopressin peak is between 6 and 9 min.]

Suitability requirements

Resolution: NLT 1.1 between the vasopressin and lypressin peaks

Relative standard deviation: NMT 2.0% for the vasopressin peak

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of vasopressin (C₄₆H₆₅N₁₅O₁₂S₂) in the portion of Vasopressin taken:

                         Result = (r_U/r_S) × (C_S/C_U) × 100

r_U = peak response from the Sample solution

r_S = peak response from the Standard solution s

C_S = concentration of USP Vasopressin RS in the Standard solution (mg/mL)

C_U = concentration of Vasopressin in the Sample solution (mg/mL)

Acceptance criteria: 95.0%-105.0% on the anhydrous, acetic acid-free basis

4 IMPURITIES

ORDINARY IMPURITIES: The sum of the responses of impurities from the Sample solution in the Assay is NMT 5% of the area of the vasopressin peak.

5 SPECIFIC TESTS

MICROBIAL ENUMERATION TESTS (61) and TESTS FOR SPECIFIED MICROORGANISMS (62): The total bacterial count is NMT 2 * 10 ^ 2 * cfu / g For products of animal origin, it also meets the requirements of the tests for absence of Salmonella species and Escherichia coli.

WATER DETERMINATION, Method Ic(921): NMT 8.0%

ACETIC ACID IN PEPTIDES (503): NMT 15.0%

6 ADDITIONAL REQUIREMENTS

PACKAGING AND STORAGE: Preserve in tight containers, preferably of Type I glass, and store in a refrigerator.

USP REFERENCE STANDARDS (11)

USP Lypressin RS

USP Vasopressin RS