Riociguat

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

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

DOWNLOAD PDF HERE

C₂₀H₁₉FN₈O₂ 422.42

Carbamic acid, N-[4,6-diamino-2-[1-[(2-fluorophenyl)methyl]-1H-pyrazolo[3,4-b]pyridin-3-yl]-5-pyrimidinyl]-N-methyl-, methyl ester;

Methyl N-(4,6-diamino-2-{1-[(2-fluorophenyl)methyl]-1H-pyrazolo[3,4-b]pyridin-3-yl}pyrimidin-5-yl)-N-methylcarbamate;

Methyl {4,6-diamino-2-[1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl]pyrimidin-5-yl}(methyl)carbamate CAS RN^®: 625115-55-1; UNII: RU3FE2Y4XI.

1 DEFINITION

Riociguat contains NLT 98.0% and NMT 102.0% of riociguat (C₂₀H₁₉FN₈O₂), calculated on the solvent-free basis.

2 IDENTIFICATION

A. Spectroscopic Identification Tests 〈197〉, Infrared Spectroscopy: 197A or 197K

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

3 ASSAY

3.1 Procedure

[Note—Protect all solutions containing riociguat from light.]

Solution A: Perchloric acid in water (4:1000)

Solution B: Acetonitrile

Mobile phase: See Table 1. Return to the original conditions, and re-equilibrate the system.

Table 1

Diluent: Solution A and Solution B (20:80)

System suitability solution: 0.4 mg/mL of USP Riociguat System Suitability Mixture RS in Diluent. Sonicate to dissolve as needed.

Standard solution: 0.4 mg/mL of USP Riociguat RS in Diluent. Sonicate to dissolve as needed.

Sample solution: 0.4 mg/mL of Riociguat in Diluent. Sonicate to dissolve as needed.

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 210 nm

Column: 4.6-mm × 25-cm; 5-µm packing L1

Temperatures

Autosampler: 15°

Column: 40°

Flow rate: 1.0 mL/min

Injection volume: 5 µL

System suitability

Samples: Standard solution and System suitability solution

[Note—See Table 2 for relative retention times. The relative retention times for riociguat related compound B and riociguat are 0.97 and 1.0, respectively.]

Suitability requirements

Resolution: NLT 1.5 between riociguat related compound B and riociguat, System suitability solution

Tailing factor: 1.0–1.5, Standard solution

Relative standard deviation: NMT 0.85% from 6 replicate injections, Standard solution

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of riociguat (C₂₀H₁₉FN₈O₂) in the portion of Riociguat taken:

Result = (r_U/r_S) × (C_S/C_U) × 100

r_U = peak response of riociguat from the Sample solution

r_S = peak response of riociguat from the Standard solution

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

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

Acceptance criteria: 98.0%–102.0% on the solvent-free basis

4 IMPURITIES

4.1 Residue on Ignition 〈281〉: NMT 0.1%

4.2 Organic Impurities

[Note—Protect all solutions containing riociguat from light.]

Solution A, Solution B, Mobile phase, Diluent, System suitability solution, Sample solution, and Chromatographic system: Proceed as directed in the Assay.

Standard solution: 0.0004 mg/mL of USP Riociguat RS in Diluent. Sonicate to dissolve as needed.

Sensitivity solution: 0.0002 mg/mL of USP Riociguat RS in Diluent from Standard solution

System suitability

Samples: System suitability solution, Standard solution, and Sensitivity solution

[Note—See Table 2 for relative retention times. The relative retention times for riociguat related compound B and riociguat are 0.97 and 1.0, respectively.]

Suitability requirements

Resolution: NLT 1.5 between riociguat related compound B and riociguat, System suitability solution

Relative standard deviation: NMT 5.0%, Standard solution

Signal-to-noise ratio: NLT 10, Sensitivity solution

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of each individual impurity in the portion of Riociguat taken:

Result = (r_U/r_S) × (C_S/C_U) × 100

r_U = peak response of each individual impurity from the Sample solution

r_S = peak response of riociguat from the Standard solution

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

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

Acceptance criteria: See Table 2. The reporting threshold is 0.05%.

Table 2

ᵃ Methyl {4,6-diamino-2-[1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl]pyrimidin-5-yl}carbamate; also known as Nelociguat.

ᵇ Isopropyl {4,6-diamino-2-[1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl]pyrimidin-5-yl}(methyl)carbamate.

5 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in tight containers. Store at controlled room temperature.

USP Reference Standards 〈11〉

USP Riociguat RS

USP Riociguat System Suitability Mixture RS

This is a mixture containing the following components:

Riociguat

Riociguat related compound B:

Methyl {4,6-diamino-2-(1-benzyl-1H-pyrazolo[3,4-b]pyridin-3-yl)pyrimidin-5-yl}(methyl)carbamate.

C₂₀H₂₀N₈O₂ 404.43

Riociguat related compound C:

Methyl {4-amino-2-[1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl]-6-(methylamino)pyrimidin-5-yl}(methyl)carbamate.

C₂₁H₂₁FN₈O₂ 436.45  (USP 1-Dec-2021)