Chlortetracycline 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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(This monograph has been updated to the current USP style. No revisions or changes to tests have been made.) 

1 DEFINITION 

Chlortetracycline Hydrochloride Ointment contains NLT 90.0% and NMT 125.0% of the labeled amount of chlortetracycline hydrochloride (C₂₂H₂₃ClN₂O₈.HCl) in a suitable ointment base. 

2 ASSAY 

Procedure 

Standard: USP Chlortetracycline Hydrochloride RS 

Sample stock solution: Use an accurately weighed quantity of Ointment, equivalent to about 30 mg of chlortetracycline hydrochloride, shaken in a separator with about 50 mL of ether, and extracted with four 20-mL portions of 0.01 N hydrochloric acid. Combine the aqueous extracts in a 100-mL volumetric ask, dilute with 0.01 N hydrochloric acid to volume, and mix. 

Sample solution: Dilute the Sample stock solution quantitatively and stepwise with water to obtain a Test Dilution having a concentration assumed to be equal to the medium dose level of the Standard. 

Analysis: Proceed as directed for chlortetracycline in Antibiotics—Microbial Assays 〈81〉. 

Acceptance criteria: 90.0%–125.0% 

3 PERFORMANCE TESTS 

Minimum Fill 〈755〉: Meets the requirements 

4 SPECIFIC TESTS 

Water Determination 〈921〉, Method I 

Analysis: Use 20 mL of a mixture of methanol and toluene (3:7) in place of methanol in the titration vessel. 

Acceptance criteria: NMT 0.5% 

5 ADDITIONAL REQUIREMENTS 

Packaging and Storage: Preserve in collapsible tubes or in well-closed, light-resistant containers. 

USP Reference Standards 〈11〉 

USP Chlortetracycline Hydrochloride RS