International legislation for the microbiological testing of non-sterile products has recently been harmonised Maria Higgins, pharmaceutical applications manager, Oxoid & Remel Microbiology - Europe, discusses the changes
The presence of certain micro-organisms in non-sterile pharmaceutical products may adversely affect the therapeutic activity of the product or even jeopardise the health of the consumer. Manufacturers are required, therefore, to ensure that the bioburden of finished products falls within acceptable limits and that they are free from potentially harmful organisms. This is achieved by implementing current Good Manufacturing Practice (cGMP) guidelines during the manufacture, storage and distribution of such products.
Microbial examination is performed by the manufacturers of non-sterile pharmaceutical products to demonstrate microbiological control during the manufacturing process. The methods used and results obtained should comply with the specifications and criteria outlined in the appropriate pharmacopoeia. Testing, which is performed on both raw materials and finished products, involves microbial enumeration tests for total aerobic microbial counts (TAMC) and total yeast and mould counts (TYMC), in addition to tests for the following specified micro-organisms: Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Salmonella, Candida albicans and Clostridium sporogenes.
Until recently, the specifications and criteria for microbial examination of non-sterile products have varied between the world's major pharmacopoeias, i.e. those of the US (USP), Europe (Ph. Eur.) and Japan (JP). Because of this, the validation and testing of products intended for worldwide markets was time-consuming and expensive, since the requirements of each region's pharmacopoeia had to be met. As a result, international groups, notably the Pharmacopoeial Discussion Group (PDG) and the International Conference on the Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH), have been working on harmonising the differing regional standards and specifications. It has taken years to obtain a text that is acceptable to the three pharmacopoeias and implementation of the harmonised chapters has required a transition period to allow the industry to adjust.
The relevant new chapters in the Ph. Eur. for microbial examination of non-sterile products are 2.6.12 Microbiological examination of non-sterile products - microbial enumeration tests, 2.6.13 Microbiological examination of non-sterile products - tests for specified micro-organisms and 5.1.4 Microbiological quality of non-sterile pharmaceutical preparations and substances for pharmaceutical use (equivalent to chapters <61>, <62> and <1111> in the USP). The major changes to these chapters are shown in the table 1.
These and additional changes to chapters 2.6.12 and 2.6.13 are explained and discussed further on the European Directorate for the Quality of Medicines (EDQM) website.1,2
The 1 January 2009 deadline for implementing the revised chapters in the Ph. Eur. (with acceptance criteria expressed as total aerobic microbial count, TAMC, and total yeast and mould count, TYMC) has now been reached, and so the harmonised methods (Set 2), as detailed in
chapters 2.6.12 and 2.6.13 of the Ph. Eur., should now be used for new applications for marketing authorisation and already-authorised products (not covered by a monograph).3,4 Similarly, the corresponding harmonised acceptance criteria for microbiological quality (Set 2) detailed in Chapter 5.1.4 of the Ph. Eur. should now be used.5
It should be noted that some additional changes to chapters 2.6.12 and 2.6.13 of the Ph. Eur. have just been published in Ph. Eur. supplement 6.56 In each of these chapters, it now states that a negative control should be performed when testing products and that a failed negative control requires further investigation. Additional changes are as follows: in the section regarding Salmonella testing (indication properties) in chapter 2.6.13 (Tests for specified micro-organisms), the agar XLD (Xylose, Lysine, Deoxycholate) no longer requires to be inoculated with Escherichia coli, due to difficulties in growing this species on this medium; the description of the test for Clostridia has been reworded to improve consistency; and the statement regarding recommended solutions and culture media, "Other media may be used if they have similar growth promoting and inhibitory properties", has been reworded, as it was considered misleading. The new wording is, "Other media may be used provided that their suitability can be demonstrated".
Microbial examination of non-sterile products has a quantitative and a qualitative phase of testing. The quantitative phase is microbial enumeration, where the total number of viable aerobic micro-organisms, yeasts and moulds are counted. The qualitative phase searches for specific micro-organisms that could be potentially pathogenic to the consumer, to ensure that products are free from such risks.
The methods used should be validated. Preparatory testing is performed to validate the chosen methods for individual products, to ensure that the product has no inhibitory effect on the recovery of any micro-organisms present or, if it does, to remove or neutralise such effects. The harmonised methods provide more detail in terms of demonstrating method suitability (validation) and media growth promotion.
Alternative methods to those described can be used if they are shown to be equivalent to the reference methods. It is important, therefore, for alternative methods to be validated against the reference methods described in Ph. Eur. 2.6.12 and Ph. Eur. 2.6.13.
With years of experience supplying culture media to the pharmaceutical industry, Oxoid and Remel's product ranges are designed to help manufacturers comply with the changing regulatory requirements, offering the complete range of recommended culture media for the microbiological examination of non-sterile products. Also, these media have been validated according to the recommended methods of the Ph.Eur, USP and JP, saving time for pharmaceutical microbiologists and giving them full confidence in the products. Furthermore, the validation document (VALPRO 003) and validation reports are available on request, and technical experts are on hand to discuss how the validation studies were implemented, if required.
Quality control of each medium is performed quantitatively and qualitatively, using the recommended strains and incubation/temperature parameters outlined in the microbial examination of non-sterile products chapters of the Ph. Eur., USP and JP.
Oxoid and Remel culture media are available in dehydrated or prepared media formats, to suit the needs of every laboratory. In addition, the complete range of specified ATCC* microbial strains recommended in the microbial examination of non-sterile products chapters of the Ph Eur, USP and JP are also available in vials that consistently deliver a specific range of colony forming units (Oxoid Quanti-Cultplus); or in disposable bacteriological loops containing stabilised micro-organisms (Oxoid Culti-Loops).
Quanti-Cultplus and Culti-Loops are ideal for use in a number of quality control procedures, including performance testing and method validation, microbial examination, bioburden testing, bacteriostasis and fungistasis testing, and growth promotion testing. They can also be used in the maintenance of stock cultures.
Harmonisation of the pharmacopoeias has taken years of planning and discussion, but it is an important achievement that will improve the registration, market surveillance and free movement/trade of medicines around the world. By reducing the work and cost involved in bringing products to the international market, this should ultimately benefit patients and consumers by reducing delays in the availability of new products.
