A review of fungal contamination in pharmaceutical products and phenotypic identification of contaminants by conventional methods
A review of fungal contamination in pharmaceutical products and phenotypic identification of contaminants by conventional methods (PDF Download Available). Available from: https://www.researchgate.net/publication/275335972_A_review_of_fungal_contamination_in_pharmaceutical_products_and_phenotypic_identification_of_contaminants_by_conventional_methods [accessed Jun 12, 2017].
Any pharmaceutical product, whether manufactured in the hospital or industrial environment, has the potential to be contaminated with microorganisms. With sterile products, any microbial contamination presents an unacceptable risk; with non-sterile products, the implication of the contamination is dependent upon whether the microorganism can be considered ‘objectionable’, and then to the extent that it can cause patient harm (and here a risk assessment is ordinarily required)1.
There are different types of microorganisms associated with product recalls. At this stage into the 21st century, fungal contamination of nonsterile products is one of the major reasons for product recalls, production shutdowns, and losses in labour and manufacturing. This can result in a reduced shelf life by compromising product integrity or present potential health hazard to patients2. Many of the reasons are due to the lack of quality control, process control and proper testing.
Most reports relating to the contamination of pharmaceutical products centre on bacterial contamination rather than fungi. The reasons for this may relate to few ‘microbiology’ laboratories in pharmaceutical organisations having trained mycologists; to an underestimation of the association between fungi and product contamination incidents; and due to a lack of appreciation of the risks that fungi can pose to cleanrooms and controlled environments3. This article considers some of these issues and, in doing so, argues that the contamination risk posed by fungi to pharmaceutical products is greater than the level of industrial and academic interest would suggest.
Fungal contamination risks
Fungi are more evolutionarily advanced forms of microorganisms, as compared to the prokaryotes (such as bacteria). Fungi are commonly divided into two distinct morphological forms: yeasts and hyphae (or filamentous). Yeasts are unicellular fungi which reproduce asexually by blastoconidia formation (budding) or fission4. Fungal contamination in pharmaceutical products represents a potential hazard for two reasons. First, it may cause product spoilage; the metabolic versatility of fungi is such that any formulation ingredient from simple sugars to complex aromatic molecules may undergo chemical modification in the presence of a suitable organism. Spoilage will not only affect therapeutic properties of the product but may also discourage the patient from taking the medication. Second, product contamination represents a health hazard to the patient, although the extent of the hazard will vary from product to product and patient to patient, depending on the types and numbers of organisms present, the route of administration, and the resistance of the patient to infection. https://www.europeanpharmaceuticalreview.com/24118/topics/microbiology-rmm/fungal-contamination-pharmaceutical-products-growing-menace/
In the following News, you will find questions on pharmaceutical water preparation and distribution frequently asked during our courses, as well as their respective answers. Read more here.
During our courses and conferences participants quite frequently raise questions on pharmaceutical water preparation and distribution. Therefore following you will find some of these questions and their respective answers.
Question 1: Which concentrations of ozone are required in water systems?
The technical literature delivers different information about the ozone concentrations in water systems: e.g. ISPE Baseline Water and Steam: 0.02 ppm – 0.2 ppm; Collentro, Pharmaceutical Water: 0.2 ppm – 0.5 ppm and W.Setz, Ciba-Geigy 1990: max 0.04 ppm, for sanitisation 0.05 ppm.
The indications provided by the ISPE Baseline refer to the concentration required to prevent microbial growth. One can thus assume that a concentration of 20 ppb ozone can prevent any growth.
If systemic protection is desired i.e. the constant presence of ozone in the water, lower ozone values are sufficient.
In practice, approx. 0.02 to 0.05 ppm should be sufficient for Aqua Purificata. For sanitisation, it naturally depends on the sanitation time intervals – daily or weekly. Finally, the required ozone concentration for the system should be determined within the framework of the validation for the whole system.
Question 2: How many ozone measurement points should be available in the water system?
If ozone is used for the sanitisation of the distribution system, the effect should also be proven by means of – indirectly – the determination of the KBE values on the one hand, and on the second hand through the proof that the ozone concentration is measured at the appropriate points in the water system. For this purpose, the ISPE Baseline mentions at least 3 measurement points:
- In the storage tank
- After the UV system
- In the return flow
The measurement in the storage tank shows that the concentration is sufficient during the permanent ozonisation. After the UV system, a measurement is done to assure destruction of the ozone. The post-use point in the return flow of the pipeline system is measured to prove that the ozone concentration is sufficient during sanitisation.
Question 3: Is there – from a GMP point of view – a preferred sanitisation method?
Basically, the following three sanitisation procedures are used today:
- Hot water sanitisation
- Sanitisation with steam
- Chemical sanitisation
The FDA, as well as the ISPE in its Baseline – are in favour of thermal sanitisation with steam. The Guidance for Industry: Sterile drug products produced by aseptic processing Prepared by Task Force (Japan) contains the following note:
“Since water for injection needs to be microbiologically pure, the equipment used for its production should be capable of withstanding periodic sterilization with pure steam at temperatures over 121°C for a given length of time. If steam sterilization is not possible because of low heat tolerance, an alternative sterilization or sanitization procedure (e.g., hot water or chemical agents) should be used for the equipment.”
GMP doesn’t specify any method. According to the state of the art, one should prefer sanitisation with steam.
Question 4: Is cold storage allowed in WFI systems?
For WFI and purified water, different temperatures are used. WFI is usually stored under heat.
In FDA’s Guide to Inspections of High purity Water Systems you can find two indications of temperatures which are actually contradictory. The first temperature interval is described under “System Design”. “The fist chapter basically states under “System Design” that it is recognized that hot water systems (here to understand as 65 to 80°C systems) are self sanitizing. Another temperature interval is indicated in the chapter “Piping”. This concretely means here that the Guide applies to hot 75 – 80°C circulating systems. These indications are in connection with the 6D rule:
FDA – GUIDE TO INSPECTIONS OF HIGH PURITY WATER SYSTEMS
“One common problem with piping is that of “dead-legs”. The proposed LVP Regulations defined dead-legs as not having an unused portion greater in length than six diameters of the unused pipe measured from the axis of the pipe in use. It should be pointed out that this was developed for hot 75 – 80°C circulating systems.”
It follows from the above that cold systems for WFI actually don’t comply with the requirements. Under these circumstances, it is likely that at least the FDA doesn’t accept cold WFI systems.
If appropriate measures (system design and sanitisation measures) can ensure that microbial growth is prevented, cold storage could basically be used. Different limits for cold storage can be found in guidelines and standards (Wallhäuser: 4°C; ISPE: 4° to 10°C). A sanitisation concept for cold storage determined within validation is imperative and should also consider the increased high-risk of bio film formation.
Question 5: Are sterilizing filters permitted in water systems?
The answer to that question requires the examination of the legal provisions and the standards and guidelines on the topic “Water”. The EU GMP Guide describes in a few points the requirements for facilities and equipment. Relating to the sterilizing filters, the following indications may be authorised:
- EU GMP 3.38: “Equipment should be installed in such a way as to prevent any risk of error or contamination.”
- EU GMP 3.39: “Production equipment should not present any hazard to the products.”
- EU GMP 3.36: “Manufacturing equipment should be designed so that it can be easily and thoroughly cleaned.”
- EU GMP Annex 1: “Water treatment plants and distribution systems should be designed, constructed and maintained so as to ensure a reliable source of water of an appropriate quality.”
In almost all guidelines, references are made to sterilizing filters. As an example, see the following statement from a Japanese guideline: Sterile drug products produced by aseptic processing (Japan 2006)
“As a rule, sterilizing filters should not be placed at water use points since the filters could mask microbiological contamination in the water system. Endotoxins could also be released from dead microorganisms retained in the filters. If the use of filters is unavoidable, the interval of replacement should be based on validation results.”
In this Japanese document, the position to filters is obvious: no sterilizing filters should normally be used. Yet, there can definitely be exceptions. The filters shouldn’t serve for masking too high KBE values. Finally, one should justify the use of such a filter.
Editor’s note: The following article is a follow up to a previous AlterNet piece about drugs whose dangerous side-effects emerged only after the pharmaceutical industry’s patents ran out.