Hydrocortisone and Acetic Acid Otic Solution

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

1 DEFINITION 

Hydrocortisone and Acetic Acid Otic Solution is a solution of Hydrocortisone and Glacial Acetic Acid in a suitable nonaqueous solvent. It contains NLT 90.0% and NMT 120.0% of the labeled amount of hydrocortisone (C₂₁H₃₀O₅), and NLT 85.0% and NMT 130.0% of the labeled amount of acetic acid (C₂H₄O₂). 

2 IDENTIFICATION 

Analysis: Dilute 5 mL of Otic Solution with 10 mL of water, and adjust with 1 N sodium hydroxide to a pH of about 7. Add ferric chloride TS. Acceptance criteria: A deep red color is produced, and it is destroyed by the addition of hydrochloric acid. 

The retention time of the major peak of the Sample solution corresponds to that of the Standard solution, both relative to the internal standard, as obtained in the Assay for Acetic Acid. 

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

3 ASSAY 

Acetic Acid 

Internal standard solution: Dilute 2.0 mL of anisole with methanol to 100 mL. 

Standard stock solution: 20 mg/mL of glacial acetic acid in methanol 

Standard solution: 10 mg/mL of glacial acetic acid in methanol, prepared as follows. Transfer a sufficient volume of the Standard stock solution to a volumetric flask of suitable size, add 20% of the flask volume of the Internal standard solution, and dilute with methanol to volume. 

Sample solution: Nominally 10 mg/mL of glacial acetic acid, prepared as follows. Transfer a sufficient volume of Otic Solution to a volumetric flask of suitable size, add 20% of the flask volume of the Internal standard solution, and dilute with methanol to volume. Chromatographic system 

(See Chromatography 〈621〉, System Suitability.) 

Mode: GC 

Detector: Flame ionization 

Column: 2-mm × 1.8-m glass; packed with 20% liquid phase G35 on support S1A 

Carrier gas: Nitrogen 

Flow rate: 25 mL/min 

Temperatures 

Injection port: 180° 

Detector: 220° 

Column: See Table 1. 

Table 1 

Injection volume: 4 µL 

System suitability 

Sample: Standard solution 

[Note—The relative retention times for anisole and acetic acid are 1.0 and 1.5, respectively.] 

Suitability requirements 

Resolution: NLT 1.5 between anisole and acetic acid 

Relative standard deviation: NMT 2.0% 

Analysis 

Samples: Standard solution and Sample solution 

Calculate the percentage of the labeled amount of acetic acid (C₂H₄O₂) in the portion of Otic Solution taken:

Result = (R_U/R_S) × (C_S/C_U) × 100 

R_U = peak response ratio of acetic acid to the internal standard from the Sample solution 

R_S = peak response ratio of acetic acid to the internal standard from the Standard solution S 

C_S = concentration of glacial acetic acid in the Standard solution (mg/mL) 

C_U = nominal concentration of acetic acid in the Sample solution (mg/mL) 

Acceptance criteria: 85.0%–130.0% 

Hydrocortisone 

Diluent: Dilute alcohol (1 in 2) 

Mobile phase: Acetonitrile and water (30:70) 

Standard solution: 0.5 mg/mL of USP Hydrocortisone RS in Diluent 

Sample solution: Nominally equivalent to 0.5 mg/mL of hydrocortisone from Otic Solution in Diluent Chromatographic system 

(See Chromatography 〈621〉, System Suitability.) 

Mode: LC 

Detector: UV 254 nm 

Column: 4-mm × 30-cm; packing L1 

Flow rate: 2 mL/min 

Injection volume: 20 µL 

System suitability 

Sample: Standard solution 

Suitability requirements 

Relative standard deviation: NMT 2.0% for four replicate injections 

Analysis 

Samples: Standard solution and Sample solution 

Calculate the percentage of the labeled amount of hydrocortisone (C₂₁H₃₀O₅)in the portion of Otic Solution 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 Hydrocortisone RS in the Standard solution (µg/mL) 

C_U = nominal concentration of Hydrocortisone RS in the Sample solution (µg/mL) 

Acceptance criteria: 90.0%–120.0% 

4 SPECIFIC TESTS 

pH 〈791〉 

Sample solution: Otic Solution and water (1:1) 

Acceptance criteria: 2.0–4.0 

5 ADDITIONAL REQUIREMENTS 

Packaging and Storage: Preserve in tight, light-resistant containers. 

USP Reference Standards 〈11〉 

USP Hydrocortisone RS