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Antibiotic testing (Micro essay USP81)

Antibiotic Potency Testing
Microbiological Assay & USP <81> Cylinder-Plate Method​

Overview Service

Capzer Pharmaceuticals performs cGMP antibiotic potency assays for raw materials and finished products using microbiological methods that measure growth inhibition zones. Our FDA/DEA-registered laboratory supports compendial testing for antibiotics across dosage forms including tablets, capsules, and injectables.​

Our Approach

Following USP <81> Antibiotics—Microbial Assays, we employ the cylinder-plate (cup-plate) method with standardized test organisms like Bacillus subtilis or Staphylococcus aureus. Samples and reference standards diffuse through agar, creating inhibition zones measured turbidimetrically or by zone diameter for precise potency calculation.​​

Key Capabilities

  • Cylinder-plate diffusion for qualitative/quantitative potency (Method A).
  • Turbidimetric broth assays for rapid endpoint determination (Method B).
  • Validation for specific antibiotics per EP/USP harmonized monographs.​​

Benefits for Partners

Partners obtain regulatory-compliant potency certificates supporting Nitrofurantoin development and generic antibiotic ANDAs from our ISO 17025-accredited facility. This ensures batch release and stability data for commercialization pipelines.

Other Service

Need for help?

Our expert team is here to support you with reliable pharmaceutical testing, analytical solutions, and regulatory guidance. Whether you have a query or need a customized service, we’re ready to assist you at every step.

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