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USP 71

Sterility testing of Pharmaceutical Products

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Introduction to USP 71 Sterility Testing

Sterility testing is an essential process in industries that manufacture sterile products, such as pharmaceuticals, drugs, medical equipment, and radioactive drugs. The United States Pharmacopeia (USP) 71 specifies the guidelines on how products can be tested for sterility and the criteria for acceptance to ensure that pharmaceutical products are free of microbial contamination. Manufacturers need to abide by these guidelines to ensure that the quality of their products is high and meets the GMP requirements.

Sterility testing, on its own, cannot serve as proof of absolute sterility of the product. However, it does serve as a crucial validation step in the larger sterilization and quality control protocols.

Test Organisms Used in USP 71 Sterility Testing

USP 71 Sterility Testing Method

At MIS two primary methods for sterility testing are followed: Membrane Filtration and Direct Transfer Sterility Testing. 

Membrane Filtration Method

The membrane filtration method is a standard test method that is used for assessing filterable pharmaceutical products. This method is applicable to products that contain preservatives, bacteriostatic agents and fungistatic agents to inhibit the growth of microorganisms.      

Procedure

  • The test samples are passed through a 0.45µm membrane filter under aseptic conditions.  
  • On completion of the filtration, the membrane filter is inoculated into a culture media* which supports the growth of the microorganisms and is incubated for 14 days. 
  • The growth of microbes in the media is analyzed.

*Growth media: Fluid Thioglycollate Medium (FTM) and Soybean Casein Digest Medium (SCDM) are used in this test. These media are used because they facilitate the growth of anaerobic bacteria, aerobic bacteria, and other microbes like fungi and yeast.

Direct Transfer Sterility Testing

  • Direct transfer sterility testing is recommended for the testing of medical products. 
  • The test method involves the transfer of sample products independently into two types of culture media, FTM and SCDM, which facilitates the growth of microorganisms. 
  • The cultures are incubated for a period of 14 days with intermittent observations. Growth of microbes in the media is analyzed.

Importance of USP 71 Sterility Testing

Sterility testing is important in ensuring the safety of patients. Infections and complications caused by contaminated products could prove to be severely dangerous to immunocompromised patients. It ensures pharmaceutical products and medical devices meet the highest standards of safety before they are released to the market. It also plays a role in validating the manufacturing process by indicating any weaknesses in their aseptic techniques or their methods of sterilization.

Applications of USP 71 Sterility Testing

Key applications of sterility testing include:

Sterility testing of pharmaceutical products

  • Injectables

It must be ensured that parenteral medications, including intravenous, intramuscular and subcutaneous injections, are sterile.

  • Ophthalmic solutions

Ophthalmic preparations such as eye drops are required to be sterile to avoid eye infections.

  • Biologicals

Biological products like vaccines, blood products and other biologics demand stringent sterility testing for their effectiveness.

Medical devices

Medical devices that are likely to come in direct or indirect contact with sterile body areas are required to undergo sterility testing.

  • Surgical instruments

Surgical instruments employed in operations should be free from microbes in order to prevent postoperative infections.

  • Catheters and implants

Products such as catheters, pacemakers and artificial joints need to be sterile before being placed inside the body to avoid any infection.

Tissue and cell products

Products derived from human or animal tissues and cells such as:

  • Tissue grafts

Tissues for bone, skin and organ transplantation have to be sterile to prevent transfer of infections in the body.

  • Cell therapies

Products involving live cells, such as stem cell therapies, must be sterile to ensure patient safety.

Nutraceuticals and parenteral nutrition

Sterility testing is also important for products meant for nutrition and dietary supplements used for human consumption.

  • Total Parenteral Nutrition (TPN)

Intravenous feed solutions given to patients should be free from bacterial contamination as patients on intravenous feeding are prone to infections.

  • Nutraceuticals

Certain high-risk dietary supplements, particularly those that are infused intravenously, may also need sterility tests prior to use in order to avoid contamination with unwanted microorganisms.

Cosmetics and personal care products

While not all cosmetics require sterility, certain products used in sensitive areas need to be sterile.

  • Products for broken skin

Cosmetics which are used on damaged skin, like wound care products, must be sterile to prevent bacterial infection.

  • Eye area products

Products like mascara, eyeliner and other items that come in contact with the eyes have to be sterile to avoid infections.

Biotechnology products

Biotech products, particularly those involving genetic engineering and cell culture, require sterility testing.

  • Recombinant proteins

Proteins synthesized using genetic engineering which are utilized in treating different diseases, should be free from contaminants.

  • Gene therapies

Products used in gene therapy techniques must be devoid of any existing impurities that may harm patients receiving these therapies.

Compounded sterile preparations

  • Hospitals and clinics

CSPs prepared in hospital and clinic pharmacies must be sterile to ensure patient safety during treatment.

Advantages of USP 71 Sterility Testing 

  • Regulatory compliance

The standard is well recognized by regulatory bodies, including the U.S. Food and Drug Administration (FDA) and the European Medicines Agency (EMA), making it a trusted standard for sterility testing.

  • Product safety

Sterility testing ensures that products intended for sterile use do not pose a risk of infection for patients.

  • Quality assurance

It validates the effectiveness of sterilization processes and ensures that manufacturing environments meet sterility requirements.

  • Versatility

The standard accommodates a wide range of product types, including liquids, solids, and devices, with specific methodologies for each.

Sterility Testing at Microbe Investigations Switzerland (MIS) – USP 71

MIS performs sterility testing of pharmaceutical products using both direct transfer and membrane filtration methods. With extensive experience in research and analysis, our specialists are at the forefront of quality assurance. Additionally, in our testing lab, we have the full capacity to do the USP 51 Preservative Challenge test.

Contact us today to discuss your sterility testing needs and ensure the safety and efficacy of your products.

FAQs

USP 71, also known as sterility testing, is performed to confirm that sterile products are free of any viable microbial contaminants.

USP <71> test is used for product sterility testing for pharmaceutical, biopharmaceutical, and medical device industries. Products to be tested using USP 71 test includes, pharmaceutical formulations, medical devices, and radiopharmaceuticals.

USP Chapter 71 test takes 1-2 weeks to complete.

We test for USP 71 using the following microbial strains: Pseudomonas aeruginosa (ATCC 15442), Escherichia coli (ATCC 8739), Staphylococcus aureus (ATCC 6538P), Enterococcus hirae (ATCC 10541), Klebsiella pneumoniae (ATCC 4352), MRSA (ATCC 33591), Salmonella enterica ( ATCC 10708), Candida Albicans (MTCC 3017). Additional strains can be added on request.

Microbiological sterility testing can be defined as the testing of pharmaceutical products or medical devices and other materials for the absence of viable microbial contaminants. It is a very important quality control check to ensure the safety of the end product.

Sterility testing is a crucial procedure that helps determine whether or not the product of interest is fit for human use. This is important in order to minimize the presence of disease-causing organisms and enhance the quality and effectiveness of the products.

Membrane filtration method and direct inoculation are the two most common methods used in sterility testing. Membrane filtration involves passing the product through a membrane which is then inoculated in culture media to see if there is any growth of microorganisms. In the direct inoculation method, the product is directly added into the culture media and later incubated to evaluate the growth of microorganisms.

Sterility testing typically takes at least 14 days to complete.

Incubation for 14 days is necessary to ensure that slow-growing microorganisms, which may have been present in the product, are detected.

The direct inoculation method is one of the test methods used in sterility testing. In this method, the required volume of the product itself is directly placed in the culture medium. The inoculated media is next incubated and examined for the presence or absence of microbial growth. This method is normally applicable if products cannot be filtered.

Some of the common media that are used in sterility testing include Fluid Thioglycollate Medium for anaerobic bacteria and Soybean-Casein Digest Medium (Tryptic Soy Broth) for aerobic bacteria and fungi.

The sterility of the culture media is determined by incubating a portion of the culture media for 14 days at a specified temperature. The absence of bacterial growth indicates that the culture media is sterile.

Membrane filter method involves passing the product through a 0.45-micron membrane filter which captures the microorganisms. This filter is then incubated in a culture medium to detect the presence of microorganisms. This method is preferred for products that can be filtered such as aqueous solutions and some oily preparations.

Sterility testing is an important quality control measure that must be adopted by all pharmaceutical manufacturers in order to ensure the safety of drugs and medical devices. It helps in verifying the effectiveness of sterilization processes and eliminating viable microorganisms.

A 0.45-micron filter is used for sterility testing because it can effectively retain bacteria and fungi while allowing the flow of the liquid product. It is a standard pore size that filters out bacteria without compromising the integrity and quality of the product.

The main methods are membrane filtration and direct inoculation. The choice of method depends on the product’s nature and formulation.

The standard is designed to detect a wide range of microorganisms, including bacteria (both aerobic and anaerobic) and fungi.

Yes, sterility testing is applicable to medical devices that require sterility, such as implants and surgical instruments.

Yes, radiopharmaceuticals can be tested using this standard. However, additional precautions may be necessary due to their radioactive nature.

Bioburden testing measures the total number of viable microorganisms on a non-sterile product, while sterility testing confirms the absence of viable microorganisms in products intended to be sterile.

The sample size depends on the product type and batch size.

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