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Determining Breathable Area Of Sterilisation Package?

For effective EtO sterilisation the packaging material must be breathable to allow the high-humidity EtO gas mixture to infiltrate the package. A partial vacuum is drawn before and after the cycle to facilitate the movement (in and out)of the EtO and moisture vapor.

If the package does not have sufficient permeability, the process will be ineffective.

A packaging that allows a breathable barrier allows sterilant to permeate during the sterilisation process while prohibiting the penetration of microorganisms during handling and storage, after sterilisation. The total package porosity of a sterilisable pouch which is dependent on the gas flow and surface area is a key for sterilisation and aeration phases of ethylene oxide gas sterilisation processes. The cycle and aeration times decrease as the porosity increases. Hence a smaller porous area is ample.

Determination of porous area requires knowledge of some specific characteristics. Breathable surface area, package volume, secondary and tertiary packaging, and peel force are all factors that determine porosity limitations. The worst case average porous area, the volume of the package and the gas exchange rate for each part of the EtO cycle at a minimum is needed for determining the porosity. The end sterilisation testing is also needed to qualify a package design. Product families of worst-case design and cycles are helpful defining the limitation of sterilisation testing, but optimizing the porosity of a package for an EtO cycle is a continuous process.

Packaging Failures: The Largest Source of Sterility Recalls

“Sterility Recalls” is a disturbing issue within the healthcare industry. “The largest source of sterility recalls [80% according to some sources] is packaging failures. Packaging design has to match product complexity.

In the changing landscape of the healthcare industry, one major change is the increase in more complex products including:

i) Combination products, such as the pairing of a delivery device and a pharmaceutical

ii) The growth of kits, and larger products made up of more items connected together whereby reducing the amount of manipulation and handling required by healthcare pros

iii) More microbiologic-centric products like skin tissues.

More complex products mean packaging/sterilization pros must consider more complex material structures, and understand that materials and products are likely to be more sensitive to sterilization.

Another part of the changing healthcare landscape is regulatory compliance. Major Factors Responsible for Packaging Failure Recalls:

• Lack Of Technical Expertise: Technical talent require thorough on-the-job training and expertise.
• Not Validated Packaging Processes
• Inappropriate Sealing
• Supplier Quality Issues
• Batch Sizes For Testing: Which may cover the issues such as no. of batches of materials to be used, sterilization stresses to be placed on packaging, etc.

Testing And Packaging Of Product With The Maximum Stress Exposure

It may be useful to test the product in the package, even though testing just the packaging is a simpler, less costly process.

Sterility assurance and packaging professionals need to work together to make sure that the testing performed will provide a safe and effective package.

Sterilization of Plastics

One of the greatest difficulties with sterilization of medical devices is the range of plastics used in any given device or kit. A simple device or kit may contain up to 10 different plastics for a range of uses, e.g. housings, tubing, connectors, valves, and seals. The plastics used may be chosen for a variety of reasons such as transparency, mechanical strength, or inertness depending on the application. The difficulty is that every plastic behaves in a different manner to the various sterilization methods used. Manufacturers can easily find that the completed device cannot be effectively sterilized. If manufacturers make unwise material choices,
then it may be impossible to adequately sterilize the completed device.

The possible sterilization methods therefore need to be considered as an integral and early part of the materials selection process for all medical devices using plastics. An additional complication in the materials selection process is the multiplicity of grades available, even for a nominally identical plastic material. For example, PVC is available in several different major materials families depending on the production method, (e.g. suspension PVC, emulsion PVC and mass polymerized PVC, and in tens of thousands of different grades which will vary according to plasticizers), fillers and other additives.

Using Steam For Sterilization

The use of steam for sterilization is fairly widespread; however, steam is seldom used as a sterilization method by the medical device industry. Most disposable plastic devices are terminally sterilized by ethylene oxide (EtO) or radiation. These processes provide low temperatures that most plastics can tolerate. Steam, however, is the most commonly used sterilization method in many healthcare facilities.

Despite its use of high temperatures, steam is a simple and inexpensive sterilization method with many benefits. It yields little waste (entropy is its only by-product). It is also efficacious in terms of its ability to kill microbial organisms.

With the growing complexity of medical device and drug combinations, it is essential to consider steam. These combination devices, such as drugs in syringes, drugs on catheters, and drug-eluting stents, often require steam sterilization because EtO cannot sterilize liquids and irradiation breaks down many drug compounds.

Steam sterilization has long been used in hospitals as well as in the pharmaceutical, aseptic processing, and food industries. Its simplicity and low capital cost make it an inexpensive, attractive, and viable sterilization method. Typical steam sterilization equipment costs less than one-third as much as an EtO chamber system and controller. It costs less than one-fourth as much as gamma or E-beam equipment and facilities.

Sterilization exposure times can range from as short as 3 minutes at 134°C to as long as 3 hours at 101°–111°C, depending upon the bioburden. Hospitals use steam at 134°C for 3 minutes for flash sterilization in emergency situations and 121°C for 15 minutes on a routine basis.

Packaging Combination Products (Medical Devices)

Packaging materials for combination devices must support all regulatory and technical requirements that relate to sterilized medical devices and pharmaceuticals. In addition, the most notable combination products, drug-eluting stents, are expensive and delicate items. Their packaging systems must be protective, high performance, and have almost zero defects to make certain these sensitive products are efficacious in use. Obviously, these products have higher value than a syringe or an oral
tablet. For that reason, medical-device manufacturers place stringent demands on combination-product-packaging materials and systems.

One of the biggest challenge is providing the required level of quality, which translates to reliability, ease of use, and surpassing rigorous -Clifford Stoll
package specs. Quality also refers to zero failures, especially zero defects in sterile barrier (sterility) properties of the package.

One bad package could make a $2,000 drug-coated stent unusable. Combination products are often used in high-risk surgical procedures so it is critical that the
package provides absolute protection for the device. At the same time, packaging materials must open easily so the product can be aseptically removed.

How Different Sterilisation Methods Were Developed ?

During time of conflict and war, new sterilization methods tend to be developed. EO sterilization was developed after WWII for germ warfare. Radiation was driven in part during the cold war as a means of using unused source of radiation. In the terrorist anthrax challenge, x-ray irradiation appears to be a practical means of sterilizing / sanitizing pallets of mail against anthrax, that other current methods couldn’t complete adequately or in time. For the first time in history we have xrays and the capability of sterilizing bulk, dense mass and large volume of untreated (contaminated) healthcare product in a matter of minutes, just in time, without the additional handling associated with unloading and loading.

The Importance of Keeping Premixed IV Bags Covered in Their Plastic Overwraps.

The Institute for Safe Medication Practice (ISMP) describes how the protective overwrap serves an important purpose - to control the amount of water vapour that escapes from an IV solution.

Once IV bags are removed from their overwraps and exposed to room air, the rate of evaporation increases. And over time, the drug’s concentration will increase because the amount of drug in the bag stays the same while amount of fluid decreases.

You can actually lose a large proportion of the liquid in an IV bag this way. ISMP cites a case where half the liquid in the bag was lost. In this case, a patient was supposed to receive 40 mEq of potassium chloride in 100 mL over an hour, but the bag was empty in half an hour. That’s because the overwrap had been removed from the bag and over time, half of the water had evaporated, leaving 40 mEq of potassium in just 50 mL of solution.

One solution may be to send them to the pharmacy, so they can be sent to a unit where a patient is currently receiving the solution and they can be used right away.
ISMP also cautions against writing an expiration date directly on the bag, because volatile chemicals from the ink may leach into the solution.


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