Tetracycline Hydrochloride Ointment

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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1 DEFINITION

Tetracycline Hydrochloride Ointment contains NLT 90.0% and NMT 125.0% of the labeled amount of tetracycline hydrochloride (C₂₂H₂₄N₂O₈ ·HCl).

2 IDENTIFICATION

Change to read:

A. (USP 1-A -2023) The retention time of the major peak of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay.

Add the following:

B. The UV spectrum of the major peak of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay. (USP 1- Aug-2023)

3 ASSAY

Change to read:

PROCEDURE

Diluent: Dimethylformamide and 0.1 M ammonium oxalate (27:68)

Mobile phase: Dimethylformamide, 0.1 M ammonium oxalate, and 0.2 M ammonium phosphate, dibasic (27:68:5). If necessary, adjust with 3 N ammonium hydroxide or 3 N phosphoric acid to a pH of 7.6–7.7.

System suitability solution: 100 μg/mL of USP Tetracy cline Hy drochloride RS and 25 μg/mL of USP 4-Epianhy drotetracy cline Hy drochloride RS in Diluent (USP 1-Aug-2023)

Standard stock solution: 1 mg/mL of USP Tetracycline Hydrochloride RS in methanol

Standard solution: 0.12 mg/mL of USP Tetracy cline Hy drochloride RS from Standard stock solution, in Diluent

Sample stock solution: Nominally 3 mg/mL of tetracycline hydrochloride prepared as follows. Transfer a weighed portion of Ointment, equivalent to 300 mg of tetracycline hydrochloride, to a glass-stoppered conical flask. Add 20 mL of cy clohexane and shake. Add 35 mL of methanol, and sonicate for about 20 min. Filter this solution into a 100-mL volumetric flask, and rinse the sides of the conical flask with 40 mL of methanol, passing the rinsing through the filter into the volumetric flask. Dilute with methanol to volume.

Sample solution: Nominally 0.12 mg/mL of tetracycline hydrochloride from the Sample stock solution, in Diluent

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 280 nm. For Identification B, use a diode array detector in the range of 200–400 nm.

Columns

Guard: 4.6-mm × 3-cm; 10-μm packing L7

Analytical: 4.6-mm × 25-cm; 5- to 10-μm packing L7

Flow rate: 2 mL/min

Injection volume: 20 μL

System suitability

Samples: System suitability solution and Standard solution

[NOTE—The relative retention times for 4-epianhydrotetracycline and tetracycline are 0.9 and 1.0, respectively.]

Suitability requirements

Resolution: NLT 1.2 between 4-epianhydrotetracycline and tetracycline, System suitability solution

Relative standard deviation: NMT 1.0%, Standard solution

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of tetracycline hydrochloride (C₂₂H₂₄N₂O₈ ·HCl) in the portion of Ointment taken:

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

r_U = peak response of tetracycline from the Sample solution

r_S = peak response of tetracycline from the Standard solution

C_S = concentration of USP Tetracy cline Hy drochloride RS in the Standard solution (mg/mL)

C_U = nominal concentration of tetracycline hydrochloride in the Sample solution (mg/mL)

P = potency of USP Tetracy cline Hy drochloride RS (μg/mg)

F = conversion factor, 0.001 mg/μg (USP 1-Aug-2023)

Acceptance criteria: 90.0%–125.0%

4 PERFORMANCE TESTS

MINIMUM FILL 〈755〉: Meets the requirements

5 SPECIFIC TESTS

WATER DETERMINATION 〈921〉 , Method I

Analysis: 20 mL of a mixture of toluene and methanol (70:30) instead of methanol in the titration vessel Acceptance criteria: NMT 1.0%

6 ADDITIONAL REQUIREMENTS

PACKAGING AND STORAGE: Preserve in well-closed containers, preferably at controlled room temperature.

Change to read:

USP REFERENCE STANDARDS 〈11〉

USP 4-Epianhydrotetracycline Hydrochloride RS

4R,4aS,12aS)-4-(Dimethylamino)-3,10,11,12a-tetrahydroxy-6-methyl-1,12-dioxo-1,4,4a,5,12,12a-hexahydrotetracene-2-carboxamide hydrochloride.

C₂₂H₂₂N₂O₇ · HCl    462.88 (USP 1-Aug-2023)

USP Tetracycline Hydrochloride RS