TGA laboratory information bulletin
Volume 7, Number 1 (March 1996)
Contents
- When is a coliform not a coliform?
- HPLC determination of procaine and benzylpenicillin in procaine penicillin injectables
- Development of a standard enrichment method for isolation of Listeria species from non-sterile therapeutic goods
- Celery preparations - a survey
- The effects of excipients in Nilstat ® Nystatin vaginal antifungal products on the tensile properties of latex rubber
- Microbial analysis of Lactobacillus products
- The design and construction of a mobile laminar flow cabinet
When is a coliform not a coliform?
The Microbiology section initiated a project to test dietary supplement powders which are listed under the Pharmaceutical Benefits scheme. Since a number of the products are foods rather than therapeutic goods, the question of applicable standards and test methods needed to be considered. TGA Laboratories (TGAL) has its own set of guidelines for assessing the results of microbiological tests on non-sterile pharmaceuticals for human use. However, in the case of milk powders, the TGAL Guidelines were considered not entirely applicable, since some of the products were foods and because the Australian Food Standards Code R7 includes microbial limits for infant formulae which are more comprehensive than the TGAL recommendations. It was decided to test for compliance with the Food Standards Code but using validated TGAL test methods as well as the Food Standards code methods. When coliform bacteria (Enterobacter agglomerans and Enterobacter cloacae) were detected using TGAL methods but not when using the Food Standards methods , Australian Capital Territory Government Analytical Laboratory (ACTGAL) were invited to conduct tests using both the Food Standards methods and TGAL methods. ACTGAL confirmed results obtained by TGAL. Repeat test in both laboratories using both sets of methods confirmed the initial results.
HPLC determination of procaine and benzylpenicillin in procaine penicillin injectables
A stability-indicating HPLC method has been developed for the assay of procaine benzylpenicillin in injectables. The method is not subject to interference form the primary hydrolytic degradation products of benzylpenicillin or from the commonly used preservative Methyl Hydroxybenzoate (Methyl paraben). The method is also suitable for the assay of procaine benzylpenicillin injections which contain Dihydrostreptomycin Sulfate or Neomycin Sulfate. A minor modification to the procedure allows the method to be applied to injections containing N,N'-dibenzyletheylene diamine (Benzathine).
Development of a standard enrichment method for isolation of Listeria species from non-sterile therapeutic goods
The genus Listeria comprises seven species of which two, L. monocytogenes and more rarely L. ivannovii, are human pathogens. Listeria species are widely distributed in the environment and are found in soil, on plants, decaying vegetation, silage, water and sewage. L. monocytogenes, the major species causing disease in both humans and animals, is often present in the digestive tracts and faeces of animals. More recently, L monocytogenes has been isolated from raw and processed foods including dairy products, meats, vegetables and seafood.
The recent association of L. monocytogenes with food-borne outbreaks of high mortality has prompted increasing concern for detection of this organism in both foods and the environment. With this in mind, the Microbiology Section considered it prudent to examine non-sterile pharmaceuticals of plant or animal origin for the presence of Listeria species.
Examination of pharmaceuticals for microbial contamination required a suitable validated procedure prior to testing. In this laboratory validation is generally performed for every product received and the micro-organisms used for this purpose do not present unnecessary hazards to staff. Validation of enrichment methods for Listeria species would entail the regular use of large volumes of fluid cultures of L. monocytogenes. In view of the fact that exposure via accidents and / or aerosols may cause a serious hazard to, or infection in lab staff, it was decided that development of a standard enrichment method for Listeria species would be microbiologically safer thereby avoiding regular use of L. monocytogenes in the laboratory.
Celery preparations - a survey
Celery is a very popular herbal remedy for a variety of complaints which has been traditionally used as an antiarthritic and an antirheumatic. Other benefits attributed to celery include 'blood purifying', regulation of bowel movements, 'stimulation of glands', and relief from gout. Its efficacy as a mild diuretic appears to have been clinically established. As part of a survey covering popular herbal preparations in the Australian markets, and following consumer over the quality of celery seed preparations available, a number of celery preparations (liquids, tablet and capsule) were tested by Thin-layer chromatography (TLC) and high performance Liquid chromatography (HPLC) for identity and approximate potency.
Overall, the liquid preparations were of adequate quality. Only five out of the nine tablet products tested were reasonably potent. The potency of the capsule preparations was very poor, two products showing not potency at all by TLC. All tablets and capsules showed very low essential oil content.
The effects of excipients in Nilstat ® Nystatin vaginal antifungal products on the tensile properties of latex rubber
Lederle Laboratories (division of Cyanamid Australia Pty Ltd) approached the TGA Adverse Drug Reactions Advisory Committee (ADRAC) in late 1993 seeking information on the interaction of particular products with contraceptive diaphragms. ADRAC had first received reports of blistering of the rubber of a diaphragm in June 1984. The then National Biological Standards Laboratory (NBSL) tested the suspect antifungal and diaphragm at the time and found 'significant decrease in tensile strength (of the diaphragm) indicating some interaction but no change in the appearance of the rubber'. Lederle Laboratories contact the then Therapeutic Devices Branch (TDB) in early 1994 seeking advice on possible interactions of particular excipients in vaginal products with diaphragms.
While TDB did not have specific information on interactions between Nilstat® vaginal products and diaphragms, there was considerable information available on the interaction of natural rubber latex with mineral oils. The bulk of the information concerned condoms but the same considerations would be true for latex rubber diaphragms. TDB proposed a study of the effect of Nilstat® vaginal preparations on the material properties of latex rubber condoms as an initial measure. Standard tests methods were available for the tensile strength testing of condoms. While not specifically testing the effects on diaphragms, the study would determine the effects on latex rubber. This would assist in determining the need for further investigations on diaphragms. A standard tensile strength test piece from a latex rubbers condom was exposed to Nystatin products (Nilstat® vaginal cream and the bulk suspension from Nilstat® Cream pessaries, supplied by Lederle Laboratories) for several time intervals and the tensile properties measured. ISO Standard 4074 testing procedures were used.
Results showed that tensile properties of latex rubber were dramatically reduced when exposed to the pessary bulk suspension. Only minimal changes were experienced with rubber samples exposed to the vaginal cream. The likely cause of the reduction in tensile strength is the presence of soft white paraffin in the pessary.
Microbial analysis of Lactobacillus products
Lactobacilli such as Lactobacillus acidophilus are part of the normal flora of the human gastrointestinal system - a correct balance of these organisms is thought to be essential for good health. This balance can be upset by the use of antibiotics, the contraceptive pill or illness. If the normal bacteria are destroyed, other bacteria resident in the gut which are not usually harmful can proliferate, possibly resulting in serious illnesses.
A study of lactobacillus species containing products was undertaken. Products came in several forms; tablet, capsule and powders. The purpose of the project was to assess the microbial quality of the therapeutics containing Lactobacillus and to enumerate and identify the Lactobacillus present. In addition, a study on the effect of storage conditions on microbiological stability was performed.
A total of 14 batches of oral products containing Lactobacillus species were tested. All batches complied with the microbial limit recommendations of the TGAL guidelines. The Lactobacillus content of all but two products was within 1 Log of the label claim. Of the seven products stored for five months, three experienced a 6 Log reduction in the counts when stored in the light at room temperature. Two products had a 3 Log reduction in counts when stored in the dark at room temperature. All products were stable when refrigerated at 2-8°C.
The design and construction of a mobile laminar flow cabinet
The workshops of the TGA Laboratories provide expertise in the design and modification of new equipment and the construction of apparatus not commercially available. The Engineering workshops recently designed and built a mobile laminar flow cabinet for use by the Sterility Testing Unit (STU). The cabinet's function was to reduce the risk of contamination during transport of equipment and clothing from a centralised preparation area to the STU. Design parameters included;
- Unrestricted access to chamber to allow easy loading and unloading.
- Minimal external dimensions to allow easy passage through doorways and corridor areas and to enable users to see over the top of the unit during the transporting of sterilised goods.
- An internal power source required.
- The unit must have as low a rolling resistance as possible.
After initial problems with lack of mobility overcome by an increase in the size of the wheels the unit was certified by the National Association of Testing Authorities (NATA) as a laminar flow workstation and is in daily service.