Chemical apparatus and process disinfecting – deodorizing – preser – Process disinfecting – preserving – deodorizing – or sterilizing
Reexamination Certificate
2000-11-28
2004-10-05
McKane, Elizabeth (Department: 1744)
Chemical apparatus and process disinfecting, deodorizing, preser
Process disinfecting, preserving, deodorizing, or sterilizing
C422S022000, C424S423000
Reexamination Certificate
active
06800245
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to sterile, polymerizable compositions together with systems, kits, and methods for the sterile manufacture, packaging, and delivery of same. More particularly, the present invention relates to sterile, polymerizable systems and kits that are comprised of pre-mixed, viscous, sterile compositions, especially restorative, and methods of making same.
BACKGROUND OF THE INVENTION
Sterilization is generally defined as rendering a substance incapable of reproduction. In terms of food, medical products or pharmaceuticals, sterilization relates to rending an article free from living microorganisms. The rate of destruction of microorganisms is logarithmic and can be described by the following expression:
N
o
/N
t
=e
−kt
wherein N
t
represents the number of organisms alive at time ‘t’, N
o
represents the initial number of organisms, and k equals the kinetic rate constant.
A common manner of expressing sterilization is the sterility assurance level (“SAL”). Because microbiological destruction is logarithmic and expressed in terms of the probability of a survivor, the term “sterile device” does not actually refer to a device that is totally free of viable organisms, but rather to one whose probability of containing a viable organism is so small that it is considered acceptable for a given purpose. Hence, the sterility assurance level (SAL) defines the probability of a viable microorganism being present on an article after sterilization is complete. According to the present FDA regulations, topical medical devices should have a minimum SAL of 10
−3
whereas devices or articles that will directly contact blood or compromised tissues should have a minimum SAL of 10
−6
. The integrity of the sterilization method is generally monitored by culturing a test organism. For example, the remaining presence of the highly heat-resistant bacterium,
bacillus subtilis globigii
, can be used as a marker to measure the completeness of sterilization.
There are many different methods of sterilization, each of which presents numerous advantages and disadvantages depending upon the nature of the article or medium to be sterilized. Some of these methods involve the application of heat, pressure, and/or moisture. Moist heat sterilization, i.e., boiling, kills all vegetative cells, most viruses, and fungi within 10 minutes. However, moist heat sterilization is not suitable for many applications in biology and medicine because it causes coagulation of proteins and breakage of hydrogen bonds contained therein.
Another method of sterilization, known as steam sterilization, is the application of steam under pressure within an enclosed chamber known as an autoclave. This method subjects the media to temperatures of typically 121° C. at pressures of 15 pounds per square inch (“psi”) above ambient. Autoclave sterilization is capable of killing all microorganisms and their endospores in about 15 minutes. The efficacy of autoclave sterilization is measured by determining the presence or absence of
bacillus stearothermophilus
spores. Media or substances stable in heat may be sterilized at higher temperatures for shorter time periods; conversely, sterilization at lower temperatures require longer sterilization periods.
Dry heat sterilization may involve incineration, i.e., exposing media to high temperatures such as 180° C., or hot-air sterilization, i.e., exposing media to controlled time and temperature conditions. This method is suitable for media such as pharmaceutical products that do not contain water as their primary solvent and cannot be sterilized by other methods. In this instance, dry heat is applied to the media at temperatures of about 100° C. to about 250° C. and exposure times ranging from about one to four hours. The temperature-time relationship is similar to that of steam sterilization.
Sterilization can also occur through the filtration or the physical retardation of microorganisms from a fluid medium by a filter membrane.
Still other methods of sterilization involve the application of radiation, either ionizing or non-ionizing, to sterilize the media. Ionizing radiation involves the application of shorter wavelength radiation, such as gamma rays, beta-rays, x-rays, or high energy electron beams, to ionize the water particles contained within the media to form reactive hydroxyl radicals. This method is commonly used to sterilize pharmaceutical products or disposable dental and medical supplies such as syringes, gloves, or sutures. Activated resins such as those used in bone cements, however, cannot be gamma sterilized because it effects the polymerization process. Non-ionizing radiation involves the application of ultraviolet rays to cause the formation of thymine dimers that inhibit the replication of DNA. Although these rays are non-penetrating to the media, some media can be destroyed in the doses required for effective sterilization.
Another sterilization method is gas sterilization, in which the media is exposed to a vapor or gas such as ethylene oxide (“EtO”). This method is suitable for media, such as foods, pharmaceuticals, and medical equipment, that cannot withstand the temperatures and moisture of steam sterilization or cannot be exposed to radiation. A gaseous sterilant, such as ethylene oxide, is applied under controlled temperature, time, gas concentration, and relative humidity parameters that vary depending upon the nature of the media to be sterilized. Important considerations in the selection of a gas sterilant is the ability of the residue remaining on the media after exposure to the sterilant to volatilize quickly. Because gas sterilization may involve the use of chlorofluorocarbons (“CFC”), plasma gas sterilization, which is a low temperature gas sterilization process involving hydrogen peroxide or other sterilants in the plasma state, is an alternative that is generally safe for the environment. However, plasma technology is currently even more limited than EtO sterilization in terms of what media it can sterilize.
Once an article is sterilized, it needs to be packaged in a manner that will not compromise its sterility until use. Sterilization packaging typically takes place at one location prior to use of the medium, or article, at another location. The main purpose of this packaging is to protect the sterility of the internal contents. Terminal sterilization describes the process of placing an article within its protective container and subsequently sterilizing the container and the article contained therein. On the other hand, aseptic processing involves placing individually sterilized components that have been sterilized by various sterilized methods into a sterilized package that is sealed under sterile conditions. The packaging containers used in these processes are sterilized separately and remain in a sterile environment prior to use. The packaging machinery that is used to fill the packaging containers is also sterilized using steam, sterile gases, or hydrogen peroxide.
Pharmaceutical products are typically rendered sterile by aseptic processing. In aseptic processing, the separate ingredients of a medium, such as a pharmaceutical, are available in sterile form and compounded without microbial contamination. Pharmaceuticals that are injectable may be comprised of aqueous or oily solutions, suspensions or emulsions, and are prepared by conventional manufacturing methods, with special care taken to remove all extraneous particulate matter. Injections must be sterilized by any of the methods given above or terminally sterilized. Some aqueous injectables are not stable and need to be prepared at the time of use by mixing some components prior to use. In this instance, the end user is provided a kit and must assemble the ingredients in a sterile environment immediately prior to injection.
An example of a multi-component system, that must be assembled by the end-user in a sterile environment prior to use, are biocompatible, restorative compositions or biomaterials that are used in orthopae
Erbe Erik M.
Prabhu Vasanth
Wicklund Jeffrey J
Wilkes Anthony M.
McKane Elizabeth
Vita Special Purpose Corporation
Woodcock & Washburn LLP
LandOfFree
Sterile polymerizable systems and kits and methods of their... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Sterile polymerizable systems and kits and methods of their..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Sterile polymerizable systems and kits and methods of their... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3272339