Patent Description:
The objective of sterilization is to destroy any microorganism in the vegetative state, or spores, and is achieved by means of standardized physical and/or chemical processes, which can be repeated and can be documented. The wet steam sterilization process performed by means of an autoclave is controlled on the basis of three physical parameters - temperature, pressure, and exposure time - the control of which is fundamental for ensuring good success of the process.

The term "saturated steam" means water vapor saturated with liquid water. This condition is possible only when the liquid phase is in equilibrium with the gaseous phase. At ambient pressure this occurs only at <NUM>, however it occurs theoretically at any temperature, provided the pressure is appropriate. Wet steam sterilization is performed in an autoclave. In this apparatus water vapor is used, which has the advantage of a high thermal capacity combined with the ability to penetrate into porous bodies of the devices.

In a terminal steam sterilization process, in order to obtain an SAL (sterility assurance level) of <NUM>-<NUM> (SAL: the probability that a single unit is not sterile of <NUM> in <NUM> million) starting from a defined level of initial contamination, according to that defined in the Official European Pharmacopoeia, the ideal relationship between these parameters is:.

Right at the start of the <NUM>, the European Committee of Standardization issued standards aimed at stabilizing the structural requirements on sterilization equipment for medical devices (European standard): more specifically EN <NUM> and EN <NUM> for validation of the process, the latter having since been superseded by UNI EN <NUM>-<NUM> and <NUM>.

The standardized hot steam sterilization processes have implementation temperatures between <NUM> and <NUM>, overpressures between <NUM> Atm and <NUM> Atm, and exposure times between <NUM> and <NUM> minutes. This sterilization method is used generally for solid bodies such as laboratory or operating theatre instruments and equipment.

At the temperatures defined by the Pharmacopoeia it is impossible to sterilize other types of products formed by heat-sensitive materials or products packaged in plastics material:.

In the prior art this type of medical device is therefore sterilized by way of other methods, such as radiation. The use of radiation, however, is not advised in a pharmaceutical environment since the substances subjected to irradiation undergo alterations anyway, to a greater or lesser degree. <CIT> and <CIT> disclose methods for sterilising gauzes and impregnated wipes respectively.

The object of the present invention is to provide a process for wet sterilization under heat, which process is effective and applicable to products closed in a bag, such as some types of medical devices, for example cloths or mitts of non-woven fabric soaked in an aqueous solution having detergent or antiseptic properties.

In the context of the present description the term "about", when used with reference to a temperature, indicates a tolerance of ± <NUM>, preferably ± <NUM>, whereas when used with reference to a pressure it indicates a tolerance of ± <NUM> bar, preferably of ± <NUM> bar.

The term "heat-sensitive", as well as the term "thermolabile", in the context of the present description, means materials that tend to deform and/or become damaged with rising temperature. An example of thermolabile materials is constituted by the plastic materials usually used in the primary packaging of medical products or devices, such as cloths, gauze and/or mitts, for example polyethylene, which deforms beyond <NUM>. Polyethylene therefore is not suitable for the primary packaging of medical devices for the skin, since these are subjected to a sterilization process at temperatures greater than <NUM>.

The term "heat-resistant", in the context of the present description, means resistance to a temperature of about <NUM>, without deformation or damage. For example, the material used for the preparation of the heat-sealed packaging with facilitated opening described herein can be a multi-layer plastic film with an aluminum layer or composite laminate packaging material which comprises a cast material (or obtained by means of a cast extrusion process) which, when exposed to a temperature of <NUM>, does not undergo any kind of alteration of its physico-chemical properties. In other words, thanks to the content of the cast material, for example cast polypropylene, it is possible to counteract the deformation of the packaging during the sterilization process caused by temperature and pressure.

The term "mitt" in the context of the present invention means a type of medical device in the form of a glove without fingers for treatment of the skin.

The invention described herein by means of the introduction of modifications to the known procedures makes it possible to achieve both sterility of the product and resistance thereof to the sterilization process. The modifications brought to the process make it possible to apply the saturated steam sterilization also to medical devices that, before now, could not be processed due to the deterioration of their properties and functions.

The innovation introduced by the present invention consists of the application of a saturated steam sterilization to various products among those typically subjected to this treatment. The reasons as to why the process is effective on this type of product lie in the fact that it is not the steam generated by the autoclave that realizes the process of sterilization within the product, given its penetrative power, but instead the steam produced within the bag, since this is a closed system. The steam of the autoclave, in fact, serves to heat the product contained in the load to a temperature greater than <NUM>. In this way, within the bag containing the soaked cloths/mitts, steam is produced from the aqueous solution saturating the fabric. This internal steam denatures the proteins of any microorganisms present, killing them and providing the sterility of the product.

The modification of the values of temperature, pressure and exposure time, which currently are not included among those advised in the Pharmacopoeia, is therefore necessary in order to obtain the objective set by the present invention.

The data obtained from the present inventors confirm that it is possible to effectively sterilize the "wet" medical devices closed within plastic bags by means of the process described herein, also at a temperature of <NUM>. This is very interesting from a commercial point of view:.

Thus, the present invention relates to a process for the sterilization of cloths, gauze and/or mitts comprising the following steps:.

Preferred features of the invention are the subject of the dependent claims. Some of the advantages of the present invention are summarized hereinafter.

A further important advantage associated with the process described herein is that the pressure of two bar, in contrast to the standard methodology, makes it possible to counteract the swelling/deterioration/explosion of the sealed contents. Traditionally, in the case of rigid containers, the stopper was left open so as to allow overpressure created as a result of the evaporation of the liquid internally, caused by the heat, to escape and not deform the container or cause it to explode. In the case of traditional practice, however, it is possible, or at the very least not ruled out, that the steam originating from the autoclave may come into contact, during the cooling phase, with the solution inside the container, modifying the parameters of the solution in an uncontrolled manner. In the process according to the invention, instead, there is no contact between the saturating liquid and the steam generated by the autoclave. Compared to known sterilization processes in an autoclave, a further advantage is therefore the absence of a risk of dilution of the solution, and contact with a steam which may contain undesirable ions, such as metals absorbed by the apparatus during the production of the steam itself, is avoided.

Other advantages and features of the present invention will become clear from the following detailed description.

The present invention relates to a process for the sterilization of cloths, gauze and/or mitts.

In particular, the invention relates to the sterilization of cloths, gauze and/or mitts soaked with an aqueous solution having detergent and/or antiseptic properties. The aqueous solution used to saturate the cloths, gauze and/or mitts prior to the sterilization may comprise water in an amount equal to or greater than <NUM>% by weight and compounds and/or active ingredients having detergent and/or antiseptic activity. The solutions comprise an extract of Aloe barbadensis and/or Linoleamidopropyl pg-dimonium chloride phosphate (Phospholipid EFA <NPL>) and/or Allantoin and/or poloxamer or any combination thereof. For example, the medical devices may be suitable for the treatment of pressure sores and/or venous and arterial ulcers.

In accordance with a preferred embodiment of said cloths, gauze and/or mitts, they are made of non-woven fabric. The weight, the thickness, the composition and the type of non-woven fabric have no effect on the sterilization process. For example, the fabric can be subjected to sterilization regardless of whether it is a spunlace or needle-punched non-woven fabric. In addition, the sterilization process described herein is effective on <NUM>% viscose fabrics, on <NUM>% synthetic fabrics, and on viscose fabrics in combination with synthetic fibers such as polyesters or polyethylenes. Another advantage of the present invention is the fact that the sterilization process is applicable to various forms of product: in particular containers, for example bags, containing a single saturated cloth, gauze and/or mitt and also containers, for example bags, containing more than one of said items can be sterilized effectively. In particular, by means of the sterilization process according to the present invention, it is possible to effectively sterilize containers that contain more than one cloth, gauze and/or mitt. In one embodiment of the invention said container may contain two, three, four, five, six, seven, or eight cloths, gauzes and/or mitts. In other words the present invention also relates to a process for the sterilization, according to any one of the embodiments described herein, of cloths, gauze and/or mitts soaked by an aqueous solution and closed in a container, wherein said container may contain up to eight cloths, gauzes and/or mitts.

A further advantage of the sterilization process according to the present invention is that it does not include any alteration either of the form or content of the sterilized cloths, gauze or mitts.

In particular, the mitts described herein are obtained by means of the following production process:.

The saturated steam sterilization according to the present invention does not in any way alter the shape or content of the mitt.

The process according to the present invention provides a first step in which the soaked cloths, gauze and/or mitts are introduced into an autoclave for the successive step of sterilization.

The products are introduced into the closed autoclave in a container such that, during the sterilization, the aqueous solution, for example an aqueous solution as defined above, generates steam within the container. The container can be, for example, a packaging made of plastic or heat-sensitive material. According to one embodiment the containers of the products are packaged in a heat-sealed manner with facilitated opening in heat-resistant multilayer material, in particular in a multi-layer plastic film with an aluminum layer. According to alternative embodiments laminate bags with a mixed composition of polyester, aluminum and polypropylene can be used. According to another embodiment a composite laminate bag comprising cast polypropylene can be used.

Once introduced, the product to be sterilized in the autoclave will undergo a step of sterilization in the autoclave at about <NUM> at a pressure of about <NUM> bar for at least <NUM> minutes.

The term "about <NUM>" in the present description indicates a tolerance of ± <NUM>, preferably ± <NUM>, whereas the term "<NUM> bar" indicates a tolerance of ± <NUM> bar, preferably ± <NUM> bar.

In accordance with a preferred embodiment the following parameters are used in the autoclave:
<IMG>.

The parameters listed above are defined in Table <NUM> below:.

The sterilization procedure was performed on various medical products from WELCARE INDUSTRIES. These products were in the form of non-woven fabric CLOTHS or MITTS soaked with an aqueous solution having detergent or antiseptic properties, closed in heat-sealed packs with facilitated opening in multilayer material (plastic-aluminum film), suitable for and resistant to heat. The samples used to perform the tests were manufactured and packaged in accordance with the internal procedures of WELCARE INDUSTRIES and belonged to routine production batches. These products were, for example, Easyderm® Sterile Glove code: <NUM> and <NUM>, Easyderm® Sterile Cloth code: <NUM> and <NUM> and UCS® (code <NUM>). The process described hereinafter is particularly suitable for the sterilization of the product sold under the name UCS® (code <NUM>), that is to say a single-use sterile gauze, soaked with a solution intended for the debridement of wounds, cleaning and hydrating the perilesional area and the edges of the wound, and cleaning of the entire affected limb. The product is provided packaged in a bag, sealed on four sides, with facilitated opening and made of a multilayer film with aluminum. The non-woven fabric cloth of the gauze, of the needle-punched kind, is formed of a combination of viscose, polyester and polypropylene, saturated with a solution based on poloxamer, Aloe Barbadensis leaf extract, and Allantoin.

The steam sterilization process for medical devices of the kind described herein from the manufacturer WELCARE INDUSTRIES was performed using an Air - Steam Mixture Autoclave, however the sterilization procedure is clearly applicable with any autoclave model validated in respect of its sterility by an authorized laboratory.

The sterilization parameters used and as defined beforehand in Table <NUM> are shown below:
<IMG>.

The products sterilized in accordance with the procedure of Example <NUM> were subjected to sterility tests.

The sterility test was performed in accordance with the procedure described in standard UNI EN ISO <NUM>-<NUM>. In summary, the sample to be tested was immersed in a growth medium to promote the development of any bacteria that had resisted sterilization. At the end of the incubation period (about <NUM> weeks) it was checked whether or not microbial growth had occurred. If the test was positive (with growth), the sterilization process had been unsuccessful, and, if negative (no growth), the sterilization process had been successful. As defined by the reference standard, the absence of activity of the culture medium indicates the sterility of the analyzed sample. All the samples analyzed were sterile following the microbiological analyses. In spite of the lower temperatures during the tests, the Bowie-Dick tests (a technique used to check the correct functioning of an autoclave) always yielded positive results.

In particular, the ability to remove air and penetration of the steam in the load, which is correlated with its efficacy in the sterilization process, were verified. The test is based on the use of special card indicator which has the feature of transforming, that is to say changing color, when exposed to a certain pressure of saturated water vapor. The card is placed inside a closed container and is placed in the middle of the apparatus, and then the sterilization procedure is started. Correct functioning is confirmed if, at the end of the process, the card has transformed totally and uniformly. If not, this means that the sterilization of materials having cavities or empty hollows is not optimal. If a positive result is obtained for the Bowie-Dock test, this confirms that saturated steam is created at the used pressure and temperature values, this being an essential system property in order for sterilization to occur.

Claim 1:
A process for the sterilization of cloths, gauze and/or gloves without fingers for treatment of the skin comprising the following steps:
- introducing in an autoclave one or more cloths, gauze and/or gloves without fingers for treatment of the skin soaked of an aqueous solution, wherein said cloths, gauze and/or gloves without fingers for treatment of the skin are closed in a container whereby during the sterilization the aqueous solution generates steam inside of said container;
- perform the sterilization in autoclave at <NUM> ± <NUM> at a pressure of <NUM> bar ± <NUM> bar , wherein said aqueous solution has detergent and/or antiseptic properties and comprises an extract of Aloe barbadensis and/or Linoleamidopropyl pg-dimonium chloride phosphate (Phospholipid EFA CAS No. <NUM>- <NUM>-<NUM>) and/or Allantoin and/or poloxamer.