Chemical apparatus and process disinfecting – deodorizing – preser – Process disinfecting – preserving – deodorizing – or sterilizing – Using direct contact steam to disinfect or sterilize
Reexamination Certificate
1992-10-05
2001-03-27
Warden, Sr., Robert J. (Department: 1744)
Chemical apparatus and process disinfecting, deodorizing, preser
Process disinfecting, preserving, deodorizing, or sterilizing
Using direct contact steam to disinfect or sterilize
C422S022000, C422S024000
Reexamination Certificate
active
06207107
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to systems, for collecting and housing body fluids. More specifically, the present invention relates to apparatus and methods for housing body fluids and solutions for inactivating viral contaminants that may be present in the body fluids.
In a variety of therapies, such as transfusions and transplants, body fluids, especially blood components such as red blood cells, platelets, plasma, leukocytes, and bone marrow, are infused from one or more individuals into a patient. Although such therapies provide treatments, some of which are life saving, and cannot otherwise be provided, due to the transmission of infectious diseases there may be potential risks involved with such therapies.
By way of example, it is known that blood can carry infectious agents such as hepatitis virus, human immuno-deficiency virus (an etiological agent for AIDS), and herpes virus. Although screening methods exist to identify blood that may include such viruses, blood containing viruses, and other disease causing pathogens, such as bacteria, cannot be 100% eliminated from the pool of possible blood component supplies. Therefore, there is still a small risk that blood transfusions can transmit viral or other infections.
Accordingly, a goal of recent biomedical research has been to reduce the risk of transmitting an infectious agent by selectively inactivating or depleting pathogens present in such blood components. One approach has been to utilize photosensitive (photoactive) agents that when activated by light of the appropriate wavelength will destroy the ability of the pathogen to cause infection. The use of photodynamic therapy has been suggested as a way to eradicate infectious agents from collected blood and its components prior to storage and/or transfusion.
A number of different photoactive agents have been proposed as possibilities to be used to eradicate viral and other contaminants in body fluids. Such photoactive agents include: psoralens; porphyrins; phthalocyanines; and dyes such as methylene blue. See, for example, U.S. Pat. Nos. 4,748,120; 4,878,891; 5,120,649; and German Patent Application No. DE 39 30 510 A1 (Mohr).
Although much effort has been focussed on commercializing such methods using photoactive agents, the inventors believe that such methods are currently not commercial. Even though a commercial system for utilizing a photoactive agent to treat blood to eradicate or remove viral and other contaminants has not been developed, it is envisioned that such a system would entail combining the blood with the photoactive agent in a container and irradiating the resultant mixture with light of the appropriate wavelength.
It is known, of course, to use blood pack units to collect blood. The blood pack units include a container typically constructed from a plastic material, usually a polyvinyl chloride material. The blood pack units are connected to tubes that allow blood to be infused into the container as well as to be accessed therefrom.
Of course, blood pack units must be sterilized. Typically, sterilization takes place by steam sterilization at a temperature of above 100° C. for a predetermined period of time.
One photoactive agent that appears to be promising with respect to eradicating viruses and bacteria from blood is methylene blue. Methylene blue, 3-7-bis(dimethylamino)phenothiazine-5-ium chloride, (C
16
H
18
ClN
3
S), in the presence of light has been reported to damage DNA. Accordingly, it can be used to selectively, in a controlled manner, modify the DNA and RNA of bacterial and viral contaminants thereby inactivating the pathogens. See U.S. Pat. No. 4,950,665.
It has recently been determined, however, that if methylene blue is placed into a standard blood pack unit constructed from PVC under standard conditions and the unit is then sterilized, that at least a certain amount of the methylene blue migrates into the PVC layer reducing the methylene blue present. The specific amount of methylene blue that migrates is variable depending upon the conditions. However, envisioned methods of using methylene blue to treat blood and other body fluids require that precise amounts of methylene blue be used.
This unfortunately requires that the blood packs must be sterilized prior to methylene blue being added thereto. This can create logistical problems, as well as increase the cost of creating the product. Likewise, during the methylene blue filling process, there is the risk of contaminating the sterilized container.
SUMMARY OF THE INVENTION
Applicants have surprisingly discovered that methylene blue can be housed in certain containers, or under certain conditions, and sterilized with the blood pack unit without the methylene blue migrating into the plastic. It has been found that two of the parameters that have a great effect on preventing methylene blue from migrating into the plastic are: the type of plastic; and the pH of the methylene blue solution.
It has been surprisingly found that methylene blue does not migrate into non-PVC material as well as into PVC material under sterilization conditions. Accordingly, in one embodiment of the invention, the present invention provides a steam sterilizable housing that includes a therapeutically effective amount of methylene blue in a solution. The housing includes at least an inner surface, the surface that contacts the methylene blue solution, that is constructed from a non-PVC material.
In an embodiment, the housing is a container of a blood pack unit that is designed to receive blood or a blood component.
The housing can also be a steam sterilizable tube including a therapeutically effective amount of a viral inactivating agent for use in blood therapy. The tube defines an interior having a first and a second end. These ends are initially closed. The interior is defined by an inner surface constructed from a non-PVC material. The interior includes therein a therapeutically effective amount of methylene blue.
In an embodiment, the tube is constructed from a mono-layer material. In a further embodiment of the invention, the tube is constructed from a multi-layer material. In a preferred embodiment of such a multi-layer layer tube, the outer layer of the tube is sealable to a PVC material.
In another embodiment of the present invention, a therapeutically effective methylene blue solution is provided. The methylene blue solution is adjusted to a pH of less than 7.0 and preferably, approximately 6.3 or less and is designed to be housed in a plastic container that will e be sterilized.
In another embodiment of the invention, a steam sterilizable unit for inactivating pathogens in a body fluid is provided comprising a plastic structure housing a therapeutically effective amount of a methylene blue solution having a pH of less than 7.0 and preferably less than or equal to approximately 6.3.
In an embodiment, the plastic structure is a container designed to house blood or a blood component.
In an embodiment, the plastic structure is a tube that is coupled to a container designed to house blood or a blood component.
The present invention also provides methods for inactivating pathogens that may be present in a body fluid.
An advantage of the present invention is that a blood pack unit can be provided that includes a viral inactivating agent therein.
A further advantage of the present invention is that it provides a container including a viral inactivating agent that can be steam sterilized.
Furthermore, an advantage of the present invention is that a sterilizable tubing, that can be sealed to a PVC container, can be provided that includes a therapeutically effective amount of methylene blue.
Still further, an advantage of the present invention is to provide an improved method for inactivating pathogens that may be contained in a body fluid.
Additional features and advantages of the present invention are described in, and will be apparent from, the detailed description of the presently preferred embodiments and from the drawings.
REFERENCES:
patent: 3298597 (1967-01-01), Bellam
Debrauwere Jack
Mathias Jean-Marie
Patel Indrajit
Barrett Robert M.
Baxter International Inc.
Price Bradford R. L.
Rockwell Amy L. H.
Snider Theresa T.
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