Indocyanine Green

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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C₄₃H₄₇N₂NaO₆S₂  774.97 (USP 1-Aug-2022)

1H-Benz[e]indolium, 2-[7-[1,3-dihydro-1,1-dimethyl-3-(4-sulfobutyl)-2H-benz[e]indol-2-ylidene]-1,3,5-heptatrienyl]-1,1-dimethyl-3-(4-sulfobutyl)-, hydroxide, inner salt, sodium salt;

2-[7-[1,1-Dimethyl-3-(4-sulfobutyl)benz[e]indolin-2-ylidene]-1,3,5-heptatrienyl]-1,1-dimethyl-3-(4-sulfobutyl)-1H-benz[e]indolium hydroxide, inner salt, sodium salt CAS RN^®: 3599-32-4; UNII: IX6J1063HV.

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1 DEFINITION

Indocyanine Green contains NLT 89.0% and NMT 100.0% of indocyanine green (C₄₃H₄₇N₂NaO₆S₂), calculated on the dried basis. It contains

NMT 5.0% of sodium iodide (Nal), (USP 1-Aug-2022) calculated on the dried basis.

2 IDENTIFICATION

2.1 A. IDENTIFICATION TESTS GENERAL (191), Chemical Identification Tests, Sodium and Sulfate

Analysis: Incinerate a portion of Indocyanine Green and use the residue.

Acceptance criteria: Meets the requirements

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2.2 B.

Sample solution: 0.05 mg/mL of Indocyanine Green in water

Analysis: Add 10 drops of sodium hydroxide TSA (USP 1-Aug-2022) to the Sample solution and heat to about 60°. Add 10 drops of Hydrogen peroxide TS and mix.

Acceptance criteria: A red color develops within 4 min, which on standing, fades to a pale orange.

3 ASSAY

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3.1 PROCEDURE

Standard solution: 2 µg/mL of USP Indocyanine Green RS in methanol

Sample solution: 2 µg/mL of Indocyanine Green in methanol

Instrumental conditions

(See Ultraviolet-Visible Spectroscopy (857).) (USP 1-Aug-2022)

Mode: UV-Vis

Analytical wavelength: 785 nm

Cell: 1 cm

Blank: Methanol

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of indocyanine green (C₄₃H₄₇N₂NaO₆S₂) in the portion of Indocyanine Green taken:

Result = (A_U/A_S) × (C_S/C_U) × 100

A_U = absorbance of the Sample solution

A_S = absorbance of the Standard solution

C_S = concentration of USP Indocyanine Green RS in the Standard solution (µg/mL)

C_U = concentration of Indocyanine Green in the Sample solution (µg/mL)

Acceptance criteria: 89.0%-100.0% on the dried basis

4 OTHER COMPONENTS

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4.1 SODIUM IODIDE

Sample: 200 mg of Indocyanine Green

Titrimetric system

(See Titrimetry (541).) (USP 1-Aug-2022)

Mode: Direct titration

Titrant: 0.01 N silver nitrate VS

Electrode system: Silver-glass

Endpoint detection: Potentiometric

Analysis: Dissolve the Sample in 100 mL of water. Add 1 mL of nitric acid and mix. Titrate with Titrant to a potentiometric endpoint.

Calculate the percentage of sodium iodide (Nal) in the portion of Indocyanine Green taken:

Result = [(V x N x F)/W] x 100

V = volume of Titrant consumed by the Sample (mL)

N = Titrant concentration, in normality (mEq/mL)

F = equivalency factor of sodium iodide, 149.9 mg/mEq

W = weight of Sample taken (mg)

Acceptance criteria: NMT 5.0% on the dried basis

Delete the following:

5 IMPURITIES

ARSENIC (211), Procedures, Method II: NMT 8 ppm

LEAD (251)

Sample solution: A 5-mL portion of the solution prepared for the test for Arsenic (211), Procedures, Method II

Analysis: Proceed as directed for the limit test of Lead (251). Use 3 mL of Ammonium Citrate Solution, 1 mL of Potassium Cyanide Solution, and 0.5 mL of Hydroxylamine Hydrochloride Solution.

Acceptance criteria: NMT 10 ppm (USP 1-Aug-2022)

6 SPECIFIC TESTS

STERILITY TESTS (71): Where the label states that Indocyanine Green is sterile, it meets the requirements.

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BACTERIAL ENDOTOXINS TEST (85): Where the label states that Indocyanine Green is sterile or must be subjected to further processing during the preparation of injectable dosage forms, the level of bacterial endotoxins is such that the requirement under the relevant dosage form monograph(s) in which Indocyanine Green is used can be met. (USP 1-Aug-2022)

LOSS ON DRYING (731)

Analysis: Dry under vacuum at 50° for 3 h.

Acceptance criteria: NMT 6.0%

7 ADDITIONAL REQUIREMENTS

PACKAGING AND STORAGE: Preserve in well-closed containers. Store at 25°, excursions permitted between 15° and 30°.

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LABELING: Where it is intended for use in preparing injectable dosage forms, the label states that it is sterile or must be subjected to further processing during the preparation of injectable dosage forms to ensure acceptable levels of bacterial endotoxins. (USP 1-Aug-2022)

USP REFERENCE STANDARDS (11)

USP Indocyanine Green RS