Contracting Sterility Testing to a GMP Certified Laboratory

Sterility testing of pharmaceutical products is a mandatory requirement when bringing a drug to market and assessing longer term safety. There are various options for manufacturers to facilitate this process. The most convenient way is to contract out to a good manufacturing practice (GMP) certified laboratory.

A typical contract lab offering this type of service would have a cleanroom suite incorporating Grade D (ISO class 7) compliant cleanrooms, housing Grade A isolators (ISO class 4). This will allow the lab to carry out a range of services from sterility testing projects, to method development and one-off or occasional testing for clients.

Sterility testing of pharmaceutical products will be conducted by either membrane filtration or direct inoculation. A contract lab offering full service will need to have isolators equipped with sterility test pumps and standard Grade A isolators for direct inoculation work. This is a high capital and operational cost business and will be reflected in charges for services.

Established labs will also have a large client list, leading to possible delays in testing, particularly for manufacturers who are not high-spending, regular clients.

In many cases, the contract lab will use vapourised hydrogen peroxide biodecontamination to assure aseptic transfer of samples and testing. This will give an added level of assurance that false positives or negatives will be avoided, but will also be used as an argument to quote premium rate charges for each test.

Within the options available to a drug manufacturer when considering a strategy for sterility testing is, who do you contract out to? An established, well equipped contract lab will have very low risk but high associated costs, whereas a small setup which will carry lower charges but may have associated commercial risks.

To maximise margins, a business must look at all aspects of manufacturing costs: in this case including sterility testing. A strategy for minimising costs should include the most commercially effective means for this final testing process. Outsourced testing can cost, typically from £150 to in excess of £500 per test and can carry inconvenient lead times in sending results. Lower cost testing may involve wiping in rather than hydrogen peroxide gassing, which carries the risk of inconsistent decontamination. There is also the longer term risk that costs will be increased, making it difficult to accurately budget for this service in the medium to long term.

An option open to manufacturers is to carry out the testing in house, but it is perceived that this is an expensive strategy that will adversely affect operational costs; building and maintaining the cleanroom; plus an isolator with high consumables costs. It is also a concern that moving to in-house testing will incur high costs in training staff to conduct the tests.

With the development of modern technology and the advent of automated hydrogen peroxide vapour biodecontamination, it may be surprising that:

  • It is not necessary to build a cleanroom (and use expensive personal protection equipment (PPE)) when a Grade A aseptic isolator is used for sterility testing.
  • High-cost spray and wipe consumables are also obviated when hydrogen peroxide is used.
  • Other than standards of practice (SOP) for the testing protocols, operators do not need to have extensive training as the decontamination process is fully automated and assures no false results.

A sterility test isolator with hydrogen peroxide gassing used in-house will allow a manufacturer to keep full control over-testing, and with leasing, costs in the short, medium, and long term will be understood and budgeted.

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