Minocycline Hydrochloride Capsules

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

Minocycline Hydrochloride Capsules contain the equivalent of NLT 90.0% and NMT 115.0% of the labeled amount of minocycline (C₂₃H₂₇N₃O₇).

2 IDENTIFICATION

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

3 ASSAY

3.1 Procedure

Mobile phase: Dimethylformamide, tetrahydrofuran, 0.2 M ammonium oxalate, and 0.01 M edetate disodium (120:80:600:180). Adjust with ammonium hydroxide to a pH of 7.2.

System suitability solution: Dissolve 10 mg of USP Minocycline Hydrochloride RS in 20 mL of 0.2 M ammonium oxalate. Heat on a water bath at 60° for 3 h, allow to cool, and dilute with water to 25.0 mL.

Standard solution: 0.5 mg/mL of minocycline from USP Minocycline Hydrochloride RS in water. Use this solution within 3 h.

Sample solution: Nominally 0.5 mg/mL of minocycline in water from combined contents of NLT 20 Capsules. Pass through a suitable filter.

Chromatographic system

• (See Chromatography 〈621〉, System Suitability.)
• Mode: LC
• Detector: UV 280 nm
• Column: 4.6-mm × 25-cm; 5-µm packing L1
• Column temperature: 40°
• Flow rate: 1.5 mL/min
• Injection volume: 20 µL

System suitability

• Samples: System suitability solution and Standard solution
• [Note-The relative retention times for epiminocycline and minocycline are 0.7 and 1.0, respectively.]
• Suitability requirements
• Capacity factor: 5.0–11.5, Standard solution
• Resolution: NLT 4.6 between epiminocycline and minocycline, System suitability solution
• Tailing factor: 0.9–2.0 for minocycline, Standard solution
• Relative standard deviation: NMT 2.0%, Standard solution

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of minocycline (C₂₃H₂₇N₃O₇) in the portion of Capsules taken:

Result = (rᵤ/rₛ) × (Cₛ/Cᵤ) × P × F × 100

rᵤ = peak response from the Sample solution

rₛ = peak response from the Standard solution

Cₛ = concentration of USP Minocycline Hydrochloride RS in the Standard solution (mg/mL)

Cᵤ = nominal concentration of the Sample solution (mg/mL)

P = potency of minocycline in USP Minocycline Hydrochloride RS (µg/mg)

F = conversion factor, 0.001 mg/µg

Acceptance criteria: 90.0%–115.0%

4 PERFORMANCE TESTS

4.1 Dissolution 〈711〉

Medium: Water; 900 mL

Apparatus 2: 50 rpm

Time: 45 min

Detector: UV maximum at about 348 nm

Standard solution: USP Minocycline Hydrochloride RS in Medium

Sample solution: Sample per Dissolution 〈711〉. Dilute with Medium to a concentration that is similar to that of the Standard solution.

Tolerances: NLT 75% (Q) of the labeled amount of minocycline (C₂₃H₂₇N₃O₇) is dissolved.

4.2 Uniformity of Dosage Units 〈905〉

Meet the requirements

5 SPECIFIC TESTS

Water Determination, Method I 〈921〉: NMT 12.0%

6 ADDITIONAL REQUIREMENTS

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

USP Reference Standards 〈11〉

USP Minocycline Hydrochloride RS