Oxytetracycline API is a tetracycline antibiotic with broad-spectrum antibacterial activity. It is derived from the Streptomyces rimosus family and is used in pharmaceutical products for susceptible bacterial infections. Oxytetracycline belongs to the tetracycline class and works primarily by inhibiting bacterial protein synthesis.
The pharmaceutical substance is available in different forms, including Oxytetracycline Dihydrate and Oxytetracycline Hydrochloride. These forms should not be treated as chemically identical for API specifications because their molecular weights, salt/hydration states and potency calculations differ. The USP monograph for Oxytetracycline specifically identifies the material as the dihydrate, with molecular weight 496.46 g/mol.
Oxytetracycline Dihydrate has the molecular formula C₂₂H₂₄N₂O₉·2H₂O and molecular weight 496.46 g/mol. The corresponding anhydrous oxytetracycline has molecular weight 460.44 g/mol. The CAS number associated with oxytetracycline is 79-57-2, while the dihydrate is also identified by CAS 6153-64-6 in chemical databases.
Because oxytetracycline is a hydrated antibiotic substance, water content and potency are particularly important quality attributes. The USP definition uses microbiological potency rather than simply treating the API as a conventional percentage-assay small molecule. USP specifies that Oxytetracycline has a potency equivalent to not less than 832 µg of oxytetracycline per mg, calculated according to the monograph.
Oxytetracycline has historically been used in human and veterinary pharmaceutical products. It has activity against a range of Gram-positive and Gram-negative bacteria and other susceptible microorganisms.
Typical pharmaceutical applications include:
Oxytetracycline is also associated with veterinary pharmaceutical products, where tetracycline-class antibiotics remain important for susceptible bacterial infections.
Oxytetracycline belongs to the tetracycline antibiotic class. Its antibacterial activity is primarily associated with inhibition of bacterial protein synthesis through interaction with the bacterial 30S ribosomal subunit. This interferes with the incorporation of amino acids into growing peptide chains.
Its broad antibacterial spectrum historically made oxytetracycline an important antimicrobial active ingredient. The exact therapeutic application depends on the target organism, dosage form, regulatory authorization and approved product labeling.
Oxytetracycline Hydrochloride is a distinct API form with CAS 2058-46-0 and molecular formula C₂₂H₂₄N₂O₉·HCl. USP gives its molecular weight as 496.89 g/mol and specifies a potency equivalent to NLT 835 µg of oxytetracycline per mg, calculated on the dried basis.
The USP monograph for Oxytetracycline Hydrochloride specifies pH 2.0–3.0 in a 10 mg/mL solution and loss on drying NMT 2.0%, using vacuum drying at 60°C for 3 hours.
Therefore, if your CMS product is specifically Oxytetracycline Hydrochloride, the specification table should use the hydrochloride values rather than the Oxytetracycline Dihydrate values.
Oxytetracycline requires careful quality control because antibiotic potency cannot always be represented accurately by a simple conventional HPLC percentage assay. The USP monograph defines Oxytetracycline by microbiological potency and includes identification requirements such as ultraviolet absorption and chemical color reaction.
For Oxytetracycline Hydrochloride, USP identification includes UV absorption and a sulfuric-acid color reaction. The monograph also specifies crystallinity, pH, loss on drying and residual-solvent requirements.
Important quality attributes include:
Oxytetracycline is known to be sensitive to environmental conditions, and appropriate packaging and storage are important for maintaining pharmaceutical quality.
Oxytetracycline API manufacturing requires controlled fermentation or synthesis-related processing, purification, drying and analytical testing appropriate to the specific API form. Since Oxytetracycline can exist in hydrated forms and as a hydrochloride salt, the exact form should always be specified in purchase, technical and quality documentation.
For an API website, Oxytetracycline Dihydrate and Oxytetracycline Hydrochloride should preferably have separate product pages because their official USP definitions and potency specifications are different. USP identifies Oxytetracycline Dihydrate at 496.46 g/mol with potency NLT 832 µg/mg, whereas Oxytetracycline Hydrochloride is 496.89 g/mol with potency NLT 835 µg/mg on the dried basis.
| Parameter | Specification |
|---|---|
| Appearance | white to off-white crystalline powder |
| Identification | IR & HPLC compliant |
| Assay (HPLC) | 98.0% – 102.0% |
| Loss on Drying | NMT 2.0% |
| Residue on Ignition | NMT 0.5% |
| pH (1% Solution) | 2.0–3.0 |
| Individual Impurity | NMT 0.5% |
| Total Impurities | NMT 2.0% |
| Water Content | NMT 2.0% |