By Lisa Benson, Technical Writer, Multisorb Technologies
In vitro diagnostic (IVD) devices play a pivotal role in diagnosing and monitoring the health of millions of people globally. As such, ensuring the reliability, accuracy, and viability of a given device is absolutely critical. An IVD device will only remain as reliable as its packaging permits; therefore, it is imperative that the product integrity remains intact from the production line through the distribution chain to the end-user.
|Learn more about the important role sorbent solutions play in IVD devices in a related presentation by Adrian Possumato, vice president of healthcare packaging at Multisorb Technologies, at the IVD Business Strategy Conference in San Diego, November 6-8.|
IVD devices can be comprised of multiple reactants, creating a challenge for device manufacturers to package the device in such a way to protect its chemical and physical stability profile. For example, the principle portion of the reactants used in diagnostic immunoassay tests may consist of antibodies, enzymes, and other water-soluble proteins. These proteins must be kept stable and viable in order to ensure the shelf life and accuracy of the device. With this in mind, regulating the equilibrium relative humidity in the device packaging becomes critical as drying has the potential to severely denature the proteins. In addition, many proteins must be protected from oxidation and volatized compounds that may interfere with the stability or performance.
The largest threat to IVD devices, however, is moisture. Although the most common route of ingress is through imperfections in the packaging seals, it may also come from the device itself, moisture in the air during packaging, or through additional packaging or printed material in the packaging.
Similarly, but to a lesser extent, oxygen can also negatively impact the reactant chemistry stability. Normal air contains about 21% oxygen, and during packaging operations, air is trapped in the packaging headspace. This trapped air can lead to autoxidation of the reactants. Having strict tolerances on headspace and purging with nitrogen prior to sealing the packaging can reduce the oxygen levels, but in many cases this approach is not enough. Oxidation can be accelerated by other factors, such as metal ions, and it only takes a small amount of oxygen to set off a chain reaction.
Choosing the correct sorbent—whether a desiccant, oxygen absorber, or some other product—is paramount to protecting the integrity of the IVD device. For some devices, it may be enough to add a traditional, yet correctly sized, desiccant to control moisture issues. But because of the aggressive nature of traditional desiccants, this approach is only effective when the device must be kept in a very dry environment.
Furthermore, over-desiccation can change the physical performance of the device. Case in point: A reagent pad on a test strip used a hydrophilic material to promote quick distribution of the sample across the test-strip substrate. When the material encountered excessive desiccation near the substrate, it changed from hydrophilic to hydrophobic. This, of course, slowed the physical reaction time of the sample with the reagent. In situations like this where moisture needs to be regulated and not merely desiccated, an intelligent sorbent is required.
There are also times where multiple environmental management functions are required—moisture regulation, oxygen absorption, and/or volatile adsorption. An intelligent sorbent offers steady-state and multifunctional control of the packaging headspace, ensuring the device is protected throughout its required shelf life.
Without packaging and chemistry/biochemistry expertise, finding the correct sorbent can be a challenge. Not only can the wrong formulation be detrimental, the wrong amount can as well. Too little sorbent can leave the product unprotected at the late end of its shelf life, for example. Performing calculations and conducting sorbent ranging studies is a very time-consuming method for homing in on the proper sorbent, however. Fortunately, pseudoempirical modeling is an effective and accurate method for determining sorbent needs.
Modeling evaluates the IVD product’s physical and chemical characteristics, packaging specifications and data, residual moisture or oxygen in the packaging, distribution and storage environment, and the desired shelf life, and then accurately predicts the internal conditions of an IVD product package. The precision of pseudoempirical modeling results provides the pathway for the formulation of an optimized sorbent solution. Although empirical testing cannot be completely replaced, this process can significantly reduce excessive testing.
IVD device stability can only be achieved by managing the environmental influences that lead to degradation. Active packaging in the form of optimized traditional and intelligent sorbents becomes a critical aspect toward maintaining the product’s integrity throughout its expected shelf life.
|Learn how to further maximize partner relationships to protect both OTC and clinical-use IVD tests at the IVD Business Strategy Conference in San Diego, November 6-8.|