THE PRESERVATION OF OPHTHALMIC PREPARATIONS 393 Committee agrees, that each preparation be regarded in its own right and to eliminate the attitude of "which is the best preservative ?" lXlot to say, "we will use chlorhexidine, or we will use phydroxybenzoates," but to look at each particular compound, and at each formulation, because each formulation could be different and could involve the necessity of using a different kind of preservative. It is therefore advisable to have in one's armoury as many preservatives as possible and not to eliminate any unless one has to. I think that this is the approach that will be taken in England from now on, i.e. that we will look at each pre- paration and consider it on its own merits. This, as Professor lXTeuwald has mentioned, occurs in Austria. MR. W. TRI•-•-wooo: It seems to me that we are very little further forward than we were •.0 years ago. We do not have a suitable container, we have one or two eye drops that are available as single dose containers, if we can call it that. I think we have surely reached the stage when, for surgical theatre work on damaged eyes, it must be a single dose container and yet we are limited to perhaps five drugs if we do this. We then turn to the things which are available commercially none of these, as far as I know, are available in a single drop container. The point has been made about the improper use in hospital of injections by nurses. I wonder if it is generally realized what kind of a moving population we have to deal with in hospitals. The nurses are moving all the time they are in training. We have moving populations of medical staff, too. And whatever drill one lays down today is obsolete tomorrow unless people are continuously watched. With eye drops it is even worse. They are left in the hands of patients. They are liable to touch the margin which may be contaminated, and after the first drop is used, the dropper is put back again and the contents are contaminated. These are the practical problems we are up against in hospitals. For damaged eyes one must suggest single drop containers as far as possible, and the smallest possible container. DR. BRowN: I believe there are single dose units on the market, and I believe that a B.S.S. for multidose containers is on its way. Mr. Norton has details of it. MR. F. BROPHY: I confirm that there are already a small number of g ml single dose phials available on the British market, which are completely sterile. A balanced salt solution, which is completely sterile, is also shortly to be available here. MR. D. A. NORTON : A committee of the British Standards Institution has been investigating pharmaceutical containers for the last two years or so, and one of the subcommittees has been dealing with the multidose eye drop container. We recognize, I think, that the need for extemporaneously prepared preparations will go on for some time and this standard recognizes it. The main aim of the speci- fication is to produce a bottle which will withstand autoclaving when properly sealed and with the medicaments contained therein. This was the requirement for auto- claving laid down some time ago in earlier papers. I hope that this specification will be published quite shortly, and I understand that almost final agreement has been reached on this standard. DR. HARRIS : The question concerning corneal ulceration following quaternary ammonium compounds is, I think, one of concentration. Some work has been published on this. Some work was done in Australia where I believe it was shown fairly clearly that the concentration normally used to preserve eye drops does not really give any trouble, not even over long periods.

j. Soc. Cosmetic Chemists 16 395-403 (1965) ¸ 1965 Society of Cosmetic Chemists of Great Britain Hygiene in Manufacturing Plant and its Effect on the Preservation of Emulsions DOREEN L. WEDDERBURN* Presented at the Symposium on "Preservatives and Antioxidants", organized by the Pharmaceutical Society of Great Britain and the Society of Cosmetic Chemists of Great Britain, in London on I7th November 196d. Synopsis--Emulsions, which under normal circumstances are adequately preserved against microbial decomposition, can and often do break down when unusually large numbers of micro-organisms are accidentally introduced. The origins of excessive contamination frequently lie in the resin beds of demineralized water units, in filters, and in poorly designed plant which cannot be cleaned and sterilized effectively. Precautions can be taken to avoid circumstances in which bacteria and fungi can multiply in manufacturing plant, and the best ways of guarding against this are the elimination of "blind ends" and dead spaces in equipment, and meticulous attention to plant cleaning and sterilization. The washing of machinery with warm detergent solutions is often inadequate because residues of emulsion diluted with the wash-solution can provide a favourable environ- ment for rapid microbial growth in stagnation areas. Lessons in good plant design and hygienic practice can be learned from the food industry where good housekeeping is essential in the avoidance of spoilage. Modem pharmaceutical and cosmetic emulsions are more susceptible to microbial decomposition than they were in the past, because many new materials are biodegradable, and consequently more rigorous standards of cleanliness, and sterility are now needed in manufacture. In most well run factories, gross contamination of products by undesirable chemicals and frank dirt is usually avoided because such contamination is readily detected during routine testing and quality control. The unseen contamination by unusually large numbers of bacteria or fungi, which can occur from time to time, however, is probably the biggest enemy in a factory producing emulsions. Firstly, because *Unilever Research Laboratory, Isleworth, Middlesex. 395