Chemical apparatus and process disinfecting – deodorizing – preser – Process disinfecting – preserving – deodorizing – or sterilizing
Reexamination Certificate
2001-04-05
2003-12-16
Thornton, Krisanne (Department: 1744)
Chemical apparatus and process disinfecting, deodorizing, preser
Process disinfecting, preserving, deodorizing, or sterilizing
C422S025000, C422S040000, C422S041000, C422S307000, C422S308000, C604S028000, C604S029000, C604S408000, C604S409000, C604S410000, C206S219000, C206S568000, C206S570000
Reexamination Certificate
active
06663829
ABSTRACT:
The present invention concerns a method and an apparatus for reducing the degradation of heat sensitive components in medical substances during heat sterilisation, wherein the medical substances are contained in a multiple chamber recipient that comprises a first chamber with a first medical substance and at least one second chamber with an amount of a second medical substance that is smaller than that of the first medical substance, and the multiple chamber recipient is heated to a predetermined temperature for sterilising the medical substances, is held at this temperature for a predetermined time period and is subsequently cooled.
The method can, for example, be utilised with multiple chamber recipients with medical substances for parenteral feeding
utrition, however the method is in particular to be used with multiple chamber recipients that contain medical substances for generating a dialysis fluid for peritoneal dialysis.
TECHNICAL BACKGROUND
Currently, haemodialysis is mainly used for acute kidney failure while for chronic kidney failure, besides transplantation, haemodialysis and peritoneal dialysis are utilised. In the case of peritoneal dialysis, the abdominal cavity is repeatedly filled at intervals with a dialysis fluid that is then removed after a hold time. The dialysis fluid is generally a buffered ionic solution with an osmotic means, wherein currently glucose is mainly used as an osmotic means and lactate is mainly used as a buffer. In this way, urea and other substances normally removed from the kidneys and excess water can be removed from the body. These dialysis fluids are produced in factories, transferred to plastic bags of two to five liter capacity and sterilised, in a similar manner to solutions for parenteral nutrition.
A disadvantage of these dialysis fluids is the presence of degradation products. At present, it is assumed that during heat sterilisation these degradation products and the accompanying brownish colour of the fluid are produced by the glucose. It is further presumed that some of these degradation products are responsible for bioincompatability reactions generated by the dialysis fluid. Studies confirm that the degradation products react strongly with biological tissue and have a substantial effect on the immune system and the cells of the peritoneum, either alone or in combination with lactate and/or a low pH value.
Theoretically, the dialysis fluids could be rendered sterile by filtration in place of the heat sterilisation. In practice, however, this is not possible because essentially all countries stipulate that medical solutions must be sterilised by heat.
However, it is known that the degradation of glucose can be markedly reduced when the sterilisation temperature is increased and simultaneously the sterilisation time shortened. It is likewise known that the glucose degradation depends strongly on the pH value, and for example is at its lowest with a pH value between 3.0 and 3.5. However, a peritoneal dialysis fluid with such a low pH value is not permitted for the treatment of patients, for this a pH value of a little over 7 would be optimal, for example 7.1 to 7.4. As a compromise, therefore, a pH value of about 5.3 is set for conventional dialysis fluids. However, from a medical point of view, this is still too low and is probably the cause of infusion pain in some patients. Furthermore substantial amounts of degradation products are still generated during heat sterilisation, which is undesirable for the reasons already mentioned.
An improvement is proposed in WO 93/09820. In the dialysis fluid disclosed here, the glucose is isolated in a small separate second chamber from the rest of the dialysis fluid located in a first chamber. The glucose is separated in this second chamber with a high concentration and a low pH value, so that the formation of degradation products of glucose during heat sterilisation is substantially reduced. The pH value of the glucose in the separate second chamber is about 3.2, while the remainder of the solution in the larger chamber has a pH value of around 7. After mixing the glucose with the rest of the solution the mixture has a pH value of around 6.4, which offers an additional advantage in terms of tolerance by patients.
In WO 97/05852 a further development of this dialysis fluid is known in which the glucose is separated into two separate chambers, namely a second and third chamber, each with different concentrations. The concentrations are selected such that upon mixing the glucose from the second chamber with the rest of the solution in the first chamber, a dialysis fluid with a glucose concentration of 1.5% is obtained, upon mixing the clucose from the third chamber with the rest of the solution in the first chamber a glucose concentration of 2.5% is obtained, and upon mixing the glucose in the second and third chambers with the rest of the solution in the first chamber a glucose concentration of 4% is obtained. In this way, the three most useful glucose concentrations can be made available with one dialysis fluid recipient, which offers a great advantage in terms of logistics and storage. In addition, this dialysis fluid contains low amounts of degradation products as a result of the low pH values in the second and third chambers.
Although this already represents a clear reduction in the amount of degradation products in the dialysis fluid, there is still a significant amount of degradation products present owing to the high glucose concentration. As a result of the small quantities in the second and third chambers compared to that of the remaining solution in the first chamber, the glucose concentrations in these second and third chambers will be heated much faster during the heat sterilisation than the rest of the solution in the first chamber, which contains the remaining components. This leads to the glucose in the second and third chambers being held for an unnecessary long period at the sterilisation temperature, which results in the unnecessary increase in degradation products. Consequently, while a considerable reduction in degradation products is achieved compared to conventional dialysis fluids, the quantity of degradation products present is nevertheless still unnecessarily high.
Finally, it is also possible to reduce the formation of degradation products during heat sterilisation of multiple chamber recipients by means of a two step heating procedure. In this, the heating of the multiple chamber recipient in the autoclave is interrupted at a predetermined temperature, so that the temperatures in the first and second, and possibly the third, chamber can become essentially equal. Subsequently, the heating of the multiple chamber recipient proceeds to the predetermined sterilisation temperature. However, it is difficult with this procedure to find the exact intermediate temperature at which no, or only few, degradation products will be formed during the hold period.
DESCRIPTION OF THE INVENTION
In view of this background it is thus an object of the present invention to provide a method, whereby the degradation of heat sensitive components in medical substances during heat sterilisation is reduced, wherein the medical substances are contained in a multiple chamber recipient having a first chamber with a first medical substance and at least a second chamber with an amount of a second medical substance that is smaller relative to the first medical substance, and the multiple chamber recipient is heated to a predetermined temperature to sterilise the medical substances, is held at this temperature for a predetermined time and is subsequently cooled.
This object is achieved in that the second chamber with the second medical substance is thermally insulated during the heating of the multiple chamber recipient.
In this way, a method is provided that reduces the degradation of heat sensitive components in the second chamber during the heat sterilisation of multiple chamber recipients with different substances. The end product after mixing the contents of the chamber thus likewise contains
Gambro AB
Lerner David Littenberg Krumholz & Mentlik LLP
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