Aminolevulinic Acid Hydrochloride

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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C₅H₉NO₃ · HCl 167.59

5-Aminolevulinic acid hydrochloride;

5-Amino-4-oxopentanoic acid hydrochloride    CAS RN^®: 5451-09-2.

1 DEFINITION

Aminolevulinic Acid Hydrochloride contains NLT 98.0% and NMT 102.0% of aminolevulinic acid hydrochloride (C₅H₉NO₃ · HCl), calculated on the dried basis.

2 IDENTIFICATION

Change to read:

A. Spectroscopic Identification Tests 〈197〉, Infrared Spectroscopy: 197A or 197K _{(CN 1-May-2020)}

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

C. Identification Tests—General, Chloride 〈191〉: Meets the requirements

3 ASSAY

Procedure

Solution A: Water adjusted with 2 M sulfuric acid to a pH of 2.2

Mobile phase: See Table 1.

Table 1

Diluent: Methanol and Solution A (1:3)

Standard solution: 4 mg/mL of USP Aminolevulinic Acid Hydrochloride RS in Diluent

Sample solution: 4 mg/mL of Aminolevulinic Acid Hydrochloride in Diluent

3.1 Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 210 nm

Column: 2.1-mm × 10-cm; 1.7-µm packing L1

Flow rate: 0.4 mL/min

Injection volume: 5 µL

System suitability

Sample: Standard solution

Suitability requirements

Tailing factor: NMT 1.6

Relative standard deviation: NMT 0.73%

3.2 Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of aminolevulinic acid hydrochloride (C₅H₉NO₃ · HCl) in the portion of Aminolevulinic Acid Hydrochloride 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

C_S = concentration of USP Aminolevulinic Acid Hydrochloride RS in the Standard solution (mg/mL)

C_U = concentration of Aminolevulinic Acid Hydrochloride in the Sample solution (mg/mL)

Acceptance criteria: 98.0%–102.0% on the dried basis

4 IMPURITIES

Residue on Ignition 〈281〉: NMT 0.3%

Organic Impurities

Mobile phase, Diluent, and Chromatographic system: Proceed as directed in the Assay.

Standard solution: 0.04 mg/mL each of USP Aminolevulinic Acid Hydrochloride RS, USP Aminolevulinic Acid Related Compound A RS, and USP Aminolevulinic Acid Related Compound B RS in Diluent

Sample solution: 40 mg/mL of Aminolevulinic Acid Hydrochloride in Diluent

System suitability

Sample: Standard solution Suitability requirements

Relative standard deviation: NMT 10%

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of aminolevulinic acid related compound A or aminolevulinic acid related compound B in the portion of Aminolevulinic Acid Hydrochloride taken:

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

r_U = peak response of each impurity from the Sample solution

r_S = peak response of the corresponding USP Reference Standard from the Standard solution

C_S = concentration of the corresponding USP Reference Standard in the Standard solution (mg/mL

C_U = concentration of Aminolevulinic Acid Hydrochloride in the Sample solution (mg/mL)

Calculate the percentage of any unspecified impurity eluting before aminolevulinic acid related compound A in the portion of Aminolevulinic Acid Hydrochloride taken:

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

r_U = peak response of any unspecified impurity eluting before aminolevulinic acid related compound A from the Sample solution

r_S = peak response of aminolevulinic acid from the Standard solution

C_S = concentration of USP Aminolevulinic Acid Hydrochloride RS in the Standard solution (mg/mL)

C_U = concentration of Aminolevulinic Acid Hydrochloride in the Sample solution (mg/mL)

Calculate the percentage of any unspecified impurity eluting after aminolevulinic acid related compound A in the portion of Aminolevulinic Acid Hydrochloride taken:

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

U S S U

r_U = peak response of any unspecified impurity eluting after aminolevulinic acid related compound A from the Sample solution

r_S = peak response of aminolevulinic acid related compound A from the Standard solution

C_S = concentration of USP Aminolevulinic Acid Related Compound A RS in the Standard solution (mg/mL)

C_U = concentration of Aminolevulinic Acid Hydrochloride in the Sample solution (mg/mL)

Acceptance criteria: See Table 2. Disregard any impurity peak less than 0.05%.

Table 2

5 SPECIFIC TESTS

5.1 pH 〈791〉

Sample solution: 10 mg/mL in carbon dioxide–free water

Acceptance criteria: 2.5–2.9

5.2 Loss on Drying 〈731〉

Sample: 1 g

Analysis: Dry the Sample over phosphorous pentoxide under vacuum at 100°–105° for 5 h.

Acceptance criteria: NMT 0.5%

6 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in well-closed containers, and store at room temperature.

USP Reference Standards 〈11〉

USP Aminolevulinic Acid Hydrochloride RS

USP Aminolevulinic Acid Related Compound A RS

3,3’-(Pyrazine-2,5-diyl)dipropionic acid.

C₁₀H₁₂N₂O₄    224.22

USP Aminolevulinic Acid Related Compound B RS

Methyl 5-(1,3-dioxoisoindolin-2-yl)-4-oxopentanoate.

C₁₄H₁₃NO₅    275.26