Oxytetracycline Hydrochloride Soluble Powder

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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Oxytetracycline Hydrochloride Soluble Powder is a dry mixture of Oxytetracycline Hydrochloride and one or more suitable excipients. It contains not less than 90.0 percent and not more than 110.0 percent of the labeled amount of oxytetracycline hydrochloride (C₂₂H₂₄N₂O₉ · HCl).

1 Packaging and storage

Preserve in well-closed containers.

2 Labeling

Label it to indicate that it is for oral veterinary use only.

USP Reference standards 〈11〉

USP Oxytetracycline RS

3 Identification

A: Shake a quantity of Soluble Powder with methanol to obtain a solution containing about 1 mg of oxytetracycline hydrochloride per mL.

Filter if necessary to obtain a clear solution. Using the filtrate as the Test solution, proceed as directed for Method II under Identification - Tetracyclines 〈193〉.

B: The retention time of the major peak in the chromatogram of the Assay preparation corresponds to that in the chromatogram of the Standard preparation, as obtained in the Assay.

pH 〈791〉: between 1.5 and 3.0, in the solution obtained as directed in the labeling.

Loss on drying 〈731〉 - Dry about 100 mg, accurately weighed, in a capillary-stoppered bottle in vacuum at a pressure not exceeding 5 mm of mercury at 60° for 3 hours: it loses not more than 3.0% of its weight.

Minimum fill 〈755〉: meets the requirements.

4 Assay

Tetrabutylammonium hydrogen sulfate solution, Edetate disodium solution, pH 7.5 Phosphate buffer, Mobile phase, Standard preparation, System suitability solution, and Chromatographic system - Proceed as directed in the Assay under Oxytetracycline.

Assay preparation - Transfer an accurately weighed portion of the Soluble Powder, equivalent to about 100 mg of oxytetracycline hydrochloride, to a 500-mL volumetric flask, dilute with 0.01 N hydrochloric acid to volume, and mix. Pass a portion of this solution through a filter having a 0.5-μm or finer porosity. Use the filtrate as the Assay preparation.

Procedure - Proceed as directed for Procedure in the Assay under Oxytetracycline. Calculate the quantity, in g, of oxytetracycline hydrochloride (C₂₂H₂₄N₂O₉ · HCl) in each g of Soluble Powder taken by the formula:

0.5(496.90/460.44)(CP/W)(r_U/r_S)

in which 496.90 and 460.44 are the molecular weights of oxytetracycline hydrochloride and oxytetracycline, respectively; C is the concentration, in mg per mL, of USP Oxytetracycline RS in the Standard preparation; P is the assigned potency, in μg of oxytetracycline per mg, of USP Oxytetracycline RS; W is the weight, in g, of Soluble Powder taken to prepare the Assay preparation; and r_U and r_S are the oxytetracycline peak responses obtained from the Assay preparation and the Standard preparation, respectively.