Antibiotic Product Testing

Antibiotic Product Testing

Pharmacological antibiotic formulations are key in the prevention of pathogenic microorganism growth and infection. To ensure patient well-being, antibiotic products must be consistently and correctly assessed for efficacy and safety. Prior to regulatory approval and market release, antibiotic product effectiveness should be evaluated to confirm that microbial growth inhibition is achieved at concentrations that are not harmful to patients.

USP compendial guidelines outline a series of microbial and biological assays that are routinely used as quality control checks for antibiotic products. Antibiotic potency assessments determine the ideal concentration of the antibiotic itself for microbial growth inhibition, while antimicrobial effectiveness tests measure how well an antibiotic product’s overall formulation prevents microbial growth.

For best results, antibiotic product testing should be performed by seasoned professionals with experience in microbiology and compendial analytical methods. The microbiology experts at CPT Labs are well-versed in technical knowledge associated with the FDA, EPA and international pharmaceutical regulations, and are ready to serve our clients’ testing needs.

Our Antibiotic Product Testing Capabilities

CPT Labs has over 40 years of experience in consumer product testing and regulatory compliance evaluations for multiple industries including, but not limited to: pharmaceuticals, OTC drugs, consumer healthcare products, cosmetic and personal care products, specialty chemical, and medical device industries. Our seasoned microbiology specialists are highly knowledgeable in validated, compendial product quality evaluation methods and current microbial safety requirements.

CPT Labs performs all antibiotic product testing according to validated USP procedures as outlined in USP <51> Antimicrobial Effectiveness Testing, USP <1227> Validation of Microbial Recovery from Pharmacopeial Articles, and USP <81> Antibiotics—Microbial Assays. Together, this panel of approaches ensures a well-rounded analytical confirmation of antibiotic activity and product efficacy.

Sample Antibiotic Product Testing Workflow

Two main phases are required for antibiotic product testing: antibiotic potency testing and antimicrobial effectiveness testing. To ensure real-world accuracy in test results, both phases of testing should occur in the exact containers or containers similar to the intended market container packaging. Should the product containment system or formulation itself significantly change, antibiotic potency and effectiveness testing will need to be re-evaluated.

1. Antibiotic Potency Testing

Different concentrations of the antibiotic under evaluation are tested against a live microorganism to determine antibiotic efficacy overall and the precise concentration at which microbial growth is inhibited. Either the Diffusion (Cylinder-Plate) or the Turbidimetric analytical method is used to determine antibiotic potency. A five-point standard curve that is also run alongside the test antibiotic as a point of comparison. While both the Diffusion (Cylinder-Plate) Method and Turbidimetric Method both measure the ability of an antibiotic to inhibit microbial growth, the final choice of which method to use depends on the antibiotic(s) under study, as described in USP <81>.

2. Antimicrobial Effectiveness

• Method Validation Test

When first testing a product for antimicrobial effectiveness or after a significant change to product formulation and/or packaging, antimicrobial efficacy must be evaluated. However, method validation studies are required before antimicrobial efficacy can be tested. Method validation tests confirm that microorganisms can grow in a formulation to ensure accurate results when running later microorganism enumeration studies. During method validation testing, antimicrobial neutralizers are added to the product sample under evaluation and the number of microorganisms recovered following an incubation step is assessed. Method validation studies must meet neutralizer efficacy and neutralizer toxicity criteria. Neutralizer efficacy is achieved when the neutralization method successfully inhibits the inherent antimicrobial properties of the product under study, while neutralizer toxicity is confirmed when microorganism recovery is successfully impaired. Antimicrobial neutralization methods include chemical inhibition, dilution and membrane filtration and washing of the antimicrobial agent(s) in a product sample.

• Antimicrobial Challenge Test

Antimicrobial challenge testing requires the neutralized product sample(s) under evaluation to be inoculated with a defined concentration of the following microorganisms: Staphylococcus aureus (Gram-positive bacteria), Pseudomonas aeruginosa (Gram-negative bacteria), Escherichia coli (Gram-negative bacteria), Candida albicans (yeast), and Aspergillus brasiliensis (mold). Following inoculation, products are incubated for six hours (minimum) to 28 days (maximum) at ambient room temperature (20-25°C). Microorganism growth is measured in regular time intervals during incubation and compared to defined limits outlined by compendial and federal regulations. Any microbial growth over the allowed limits indicates that the product’s antimicrobial component(s) is ineffective.

Our Facilities

CPT offers several state-of-the-art Analytical, Microbiological, Clinical, Photobiology and In Vitro Toxicology laboratories for our clients’ product testing needs. Our facilities are maintained at a high level of regulatory compliance to ensure the best quality assessments of product safety, stability and efficacy. We strongly adhere to Good Laboratory Practices (GLP), Good Manufacturing Practices (GMP) and Good Clinical Practices (GCP) standards to ensure the best quality results for our clients. Custom-tailored testing programs and flexible turn-around times are available. Contact us at your earliest convenience.