Isradipine
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This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition
Issued and maintained by the United States Pharmacopeial Convention (USP)
C19H21N3O5 371.39
3,5-Pyridinedicarboxylic acid, 4-(4-benzofurazanyl)-1,4-dihydro-2,6-dimethyl-, methyl 1-methylethyl ester, (±)-;
Isopropyl methyl (±)-4-(4-benzofurazanyl)-1,4-dihydro-2,6-dimethyl-3,5-pyridinedicarboxylate CAS RN®: 75695-93-1; UNII: YO1UK1S598.
1 DEFINITION
Isradipine contains NLT 98.0% and NMT 102.0% of isradipine (C19H21N3O5), calculated on the dried basis.
2 IDENTIFICATION
Change to read:
A. Spectroscopic Identification Tests 〈197〉, Infrared Spectroscopy: 197K (CN 1-May-2020)
B. The retention time of the isradipine peak of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay.
3 ASSAY
Procedure
Use low-actinic glassware throughout this procedure, and otherwise protect the test specimen, the Reference Standard, and all solutions containing them from unnecessary exposure to light.
Mobile phase: Methanol, tetrahydrofuran, and water (400:100:500)
Standard solution: 0.2 mg/mL of USP Isradipine RS and 0.01 mg/mL of USP Isradipine Related Compound A RS in Mobile phase. If necessary, use sonication and/or add 1 mL of methanol per 20 mL of Mobile phase to dissolve the Reference Standards.
Sample solution: 0.2 mg/mL of Isradipine prepared as follows. Transfer 20 mg of Isradipine to a 100-mL volumetric flask. Add sufficient methanol to dissolve, and sonicate if necessary. Dilute with Mobile phase to volume.
Chromatographic system
(See Chromatography 〈621〉, System Suitability.)
Mode: LC
Detector: UV 326 nm
Column: 4.6-mm × 10-cm; packing L1
Flow rate: 1.7 mL/min
Injection volume: 25 μL
System suitability
Sample: Standard solution
Suitability requirements
Resolution: NLT 1.5 between isradipine and isradipine related compound A
Relative standard deviation: NMT 1.5%
Analysis
Samples: Standard solution and Sample solution
Calculate the percentage of isradipine (C19H21N3O5) in the portion of Isradipine taken:
Result = (rU/rS) x (CS/CU) × 100
rU = peak response of isradipine from the Sample solution
rS = peak response of isradipine from the Standard solution
CS = concentration of USP Isradipine RS in the Standard solution (mg/mL)
CU = concentration of Isradipine in the Sample solution (mg/mL)
Acceptance criteria: 98.0%–102.0% on the dried basis
4 IMPURITIES
Residue on Ignition 〈281〉: NMT 0.1%
Organic Impurities
Use low-actinic glassware throughout this procedure, and otherwise protect the test specimen, the Reference Standard, and all solutions containing them from unnecessary exposure to light.
Mobile phase: Prepare as directed in the Assay.
System suitability solution: 0.2 mg/mL of USP Isradipine RS and 0.01 mg/mL of USP Isradipine Related Compound A RS in Mobile phase. If necessary, use sonication and/or add 1 mL of methanol per 20 mL of Mobile phase to dissolve the Reference Standards.
Standard solution: 6 μg/mL of USP Isradipine RS in Mobile phase. If necessary, use sonication and/or add 1 mL of methanol per 20 mL of
Mobile phase to dissolve the Reference Standards.
Sample solution: 2 mg/mL of Isradipine prepared as follows. Transfer 50 mg of Isradipine to a 25-mL volumetric flask, and add 5.0 mL of methanol to dissolve. Sonicate if necessary, and dilute with Mobile phase to volume.
Chromatographic system
(See Chromatography 〈621〉, System Suitability.)
Mode: LC
Detector: UV 230 nm
Column: 4.6-mm × 10-cm; packing L1
Flow rate: 1.7 mL/min
Injection volume: 25 μL
Run time: NLT 3 times the retention time of isradipine for the Sample solution
System suitability
Sample: System suitability solution
Suitability requirements
Resolution: NLT 1.5 between isradipine and isradipine related compound A
Relative standard deviation: NMT 1.5%
Analysis
Samples: Standard solution and Sample solution
Acceptance criteria: The sum of the peak responses, other than that of isradipine, of the Sample solution is NMT 4 times the isradipine response from the Standard solution (NMT 1.2%); the response of the largest peak, other than that of isradipine, of the Sample solution is NMT 1.6 times greater than the isradipine response from the Standard solution (NMT 0.5%); no other peak response, other than that of isradipine, is greater than the isradipine response from the Standard solution (NMT 0.3%).
5 SPECIFIC TESTS
Loss on Drying 〈731〉
Analysis: Dry at 105° for 4 h.
Acceptance criteria: NMT 0.2%
6 ADDITIONAL REQUIREMENTS
Packaging and Storage: Preserve in well-closed, light-resistant containers.
USP Reference Standards 〈11〉
USP Isradipine RS
USP Isradipine Related Compound A RS
Isopropyl methyl 4-(4-benzofurazanyl)-2,6-dimethyl-3,5-pyridinedicarboxylate.
C19H19N3O5 369.38
