Oxacillin API is a semisynthetic penicillin antibiotic belonging to the beta-lactam class of antibacterial drugs. It was developed as a penicillinase-resistant penicillin and is structurally derived from the penicillin nucleus, 6-aminopenicillanic acid (6-APA). Oxacillin is particularly characterized by its resistance to inactivation by penicillinase, also known as beta-lactamase, an enzyme produced by certain bacteria that can destroy susceptible penicillins. Current U.S. labeling describes Oxacillin for Injection as a semisynthetic penicillin antibiotic and identifies oxacillin sodium as the active salt used in the parenteral dosage form.
The Oxacillin free base has the molecular formula C19H19N3O5S and molecular weight 401.4 g/mol. PubChem identifies the principal CAS number as 66-79-5, while 1173-88-2 is associated with the anhydrous monosodium salt and 7240-38-2 with oxacillin sodium monohydrate.
For pharmaceutical applications, it is important to distinguish Oxacillin from Oxacillin Sodium. Oxacillin Sodium Monohydrate has the molecular formula C19H18N3NaO5S·H2O and molecular weight 441.43 g/mol. USP identifies Oxacillin Sodium as the monohydrate and provides a specific pharmacopoeial content range based on oxacillin equivalent.
Oxacillin Sodium API is the sodium salt of Oxacillin and is the form used in the historical and current U.S. injectable pharmaceutical products. DailyMed describes Oxacillin for Injection, USP as a sterile product containing oxacillin sodium monohydrate and states that each vial contains oxacillin sodium monohydrate equivalent to 1 g or 2 g of oxacillin, depending on the product presentation.
The sodium salt is chemically designated as a monosodium salt monohydrate. Its molecular formula is C19H18N3NaO5S·H2O, and its molecular weight is 441.43 g/mol. The corresponding anhydrous sodium salt has a molecular weight of 423.43 g/mol. USP lists both forms in its monograph and associates CAS 7240-38-2 with the monohydrate and 1173-88-2 with the anhydrous salt.
Oxacillin contains the characteristic beta-lactam ring of penicillin antibiotics together with a substituted isoxazole-containing side chain. The chemical structure is responsible for its classification as an isoxazolyl penicillin and contributes to its resistance to many penicillinases.
PubChem identifies Oxacillin with PubChem CID 6196 and reports an exact mass of 401.10454189 Da for the free acid. Its calculated XLogP3 value is 2.4, hydrogen-bond donor count is 2, hydrogen-bond acceptor count is 7, rotatable-bond count is 4, and topological polar surface area is 138 Ų.
These physicochemical characteristics are useful for analytical identification, formulation development and pharmaceutical research. However, calculated chemical descriptors should not be confused with mandatory API release specifications.
Oxacillin belongs to the beta-lactam antibiotic family. Like other penicillin antibiotics, its antibacterial effect is associated with interference with bacterial cell-wall synthesis. The beta-lactam structure enables interaction with bacterial penicillin-binding proteins, thereby disrupting the transpeptidation processes required for peptidoglycan cross-linking.
One of the defining characteristics of Oxacillin is its relative resistance to hydrolysis by penicillinase (beta-lactamase). Current U.S. product labeling specifically states that Oxacillin is resistant to inactivation by penicillinase.
This property differentiates Oxacillin from penicillin antibiotics that are readily hydrolyzed by penicillinase and explains its historical development for treatment of susceptible penicillinase-producing staphylococcal infections.
Oxacillin has been used as a pharmaceutical antibacterial ingredient for susceptible bacterial infections. Current U.S. labeling states that Oxacillin for Injection is intended for treatment or prevention of infections proven or strongly suspected to be caused by susceptible bacteria.
Oxacillin is particularly associated with methicillin-susceptible Staphylococcus aureus (MSSA) and other susceptible organisms. Its historical clinical use includes serious infections caused by penicillinase-producing staphylococci when susceptibility is established.
As with all antibacterial medicines, pharmaceutical use should be based on appropriate microbiological testing, clinical indication and applicable prescribing information. API content should describe the pharmaceutical role objectively rather than presenting the raw material itself as a treatment recommendation.
Manufacturing of Oxacillin API involves controlled semisynthetic pharmaceutical chemistry beginning with an appropriate penicillin intermediate. The process requires careful control of reaction conditions, raw-material quality, intermediate purity and final purification to produce a consistent active pharmaceutical ingredient.
For Oxacillin Sodium, manufacturing additionally requires control of the sodium salt form and hydration state. This is important because the molecular weight differs between the anhydrous sodium salt and monohydrate. USP explicitly identifies the monohydrate as 441.43 g/mol and the anhydrous salt as 423.43 g/mol.
A pharmaceutical-grade manufacturing program can include controls for starting materials, process-related impurities, degradation products, residual solvents, water content, elemental impurities and microbiological quality where applicable.
Quality control for Oxacillin should differentiate between chemical identity and potency/content expressed as oxacillin equivalent. This is particularly important for Oxacillin Sodium because the USP definition does not simply specify the percentage of the complete sodium monohydrate molecule.
The USP Oxacillin Sodium monograph defines the material as containing not less than 815 µg/mg and not more than 950 µg/mg of oxacillin, corresponding to 81.5–95.0% oxacillin equivalent by mass. This is the authoritative numerical value that should be used when representing the USP definition.
This range should not be incorrectly converted into an “81.5–95.0% Oxacillin Sodium assay.” It is specifically expressed by USP as the equivalent amount of oxacillin (C19H19N3O5S) per mg of Oxacillin Sodium.
USP identifies Oxacillin Sodium as:
C19H18N3NaO5S·H2O — molecular weight 441.43
The monograph also identifies the anhydrous sodium salt as:
C19H18N3NaO5S — molecular weight 423.43
and defines the content as NLT 815 µg/mg and NMT 950 µg/mg of Oxacillin. USP reference standards include USP Oxacillin Sodium RS and USP Oxacillin Related Compound C RS.
This distinction is highly relevant for API technical documentation because it prevents incorrect reporting of the salt's potency and molecular weight.
Current DailyMed labeling describes Oxacillin for Injection as a white to off-white powder that produces a clear solution upon reconstitution. The labeled pharmaceutical product contains oxacillin sodium monohydrate and is intended for intramuscular or intravenous administration.
These characteristics refer to the finished sterile pharmaceutical product rather than necessarily to bulk Oxacillin Sodium API. Consequently, CMS technical specifications should clearly differentiate API properties from finished dosage-form characteristics.
Analytical characterization of Oxacillin API can involve spectroscopic identification, chromatographic purity testing, assay/potency determination, residual-solvent analysis, water determination and impurity profiling.
Because Oxacillin is a beta-lactam antibiotic, degradation and impurity control are particularly important. Beta-lactam compounds can undergo chemical degradation under unsuitable environmental conditions, making appropriate manufacturing, packaging and storage controls important for maintaining API quality.
Chromatographic methods can be used to monitor the active ingredient and related substances, while mass spectrometry can provide molecular-mass confirmation. The final analytical package should be based on the applicable pharmacopoeial requirements and validated product-specific methods.
Oxacillin and its sodium salt should be handled according to the applicable pharmaceutical specification and validated stability data. Finished Oxacillin injection products have specific storage and handling requirements, but those requirements should not automatically be transferred to bulk API.
For an API manufacturer, appropriate packaging should protect the material from environmental conditions that could negatively affect chemical stability. Stability studies should establish the appropriate storage conditions, retest period and packaging configuration for the specific API presentation.
An Oxacillin API manufacturer in India can provide pharmaceutical-grade Oxacillin or Oxacillin Sodium for pharmaceutical development and manufacturing applications. Accurate technical documentation should clearly identify the chemical form, CAS number, molecular formula, molecular weight and applicable pharmacopoeial requirements.
For Oxacillin Sodium Monohydrate, the principal technical identity is CAS 7240-38-2, molecular formula C19H18N3NaO5S·H2O, and molecular weight 441.43 g/mol. The USP-defined content is 815–950 µg/mg of Oxacillin equivalent.
For Oxacillin free base, the relevant identity is CAS 66-79-5, molecular formula C19H19N3O5S, and molecular weight 401.4 g/mol.
Maintaining these forms separately in CMS records helps avoid CAS-number, formula, molecular-weight and specification errors. It also creates a technically stronger SEO page for pharmaceutical customers searching specifically for Oxacillin API, Oxacillin Sodium API, Oxacillin CAS Number, and Oxacillin Sodium manufacturer in India.
| Parameter | Specification |
|---|---|
| Appearance | white to off-white crystalline powder |
| Identification | IR & HPLC compliant |
| Assay (HPLC) | 98.0% – 102.0% |