PCM – A Prescription for Precise Temperature Control-

Samit Jain, Director, Pluss Polymers

Are the medicines made to save lives are themselves safe?

The growing number of temperature-sensitive pharmaceutical products and the globalization of manufacturing sites have increased the complexity of distribution.

This complexity is pressurizing the cold chain stakeholders to continuously innovate and improvise upon the existing solutions. The most critical part in cold chain becomes the temperature controlled transport because of the variations in ambient conditions.

Phase Change Materials (PCMs) are innovative materials which offer the possibility to maintain desired temperatures with precision. They can store and release large amounts of thermal energy at constant temperature and can be integrated in cold chain as an effective solution for distribution challenges. The thermal energy transfer occurs when a material changes from a solid to a liquid or from a liquid to a solid. This is called a change in state or “phase.”

The type of shipping system must be decided by the load size, the nature of the product, the risk presented by temperatures fluctuations, and the time of exposure to adverse conditions. Larger bulk loads are easier to handle as reefer trucks or eutectic systems can be used.

But most of the pharmaceutical transport happens in small loads to various locations. These small loads are transported in insulated boxes with different kinds of packaging.

The existing solution being used for maintaining desired temperatures in these boxes are dry ice or gel packs. These have been used conventionally for decades due to the lack of a right solution. The industry seeks a solution which can eliminate disadvantages posed by these solutions which are explained below.

Dry Ice – The medicines having rubber stoppers can lose their sterility due to dry ice as at around -40’C rubber reaches its glass transition temperature. Not only this, dry ice cannot be used in air tight containers due to the expansion of particles as the solid sublimate to gas. As it sublimates it creates additional space for the product to become damaged from increased shifting. Dry ice is best used within a few days manufacturing otherwise its exposure to ambient creates a layer of wet ice.

There are also many regulations that restrict dry ice shipments mainly for three reasons.  First, it can be an explosion hazard. Second, it is a suffocation hazard based on quantity of CO2 produced. Third, dry ice is extremely cold and is a physical hazard if handled without proper protection.

Gel Packs/Ice Gels – The conventional gel packs are water gel/glycol mixtures which offer few temperature options. They have very limited energy storage capacity, so more numbers of such packs are required in a box reducing available volume for the products.

They also do not maintain precise temperatures. These packs require very long duration and considerably low temperatures to freeze causing operational issues.

Phase change materials can not only eliminate above issues but also offer many more temperature options than conventional solutions. They are non-hazardous, non-toxic materials and have very good latent heat capacity which enables them to give longer temperature back up with smaller amounts.

Phase Change Materials are available in different encapsulations like HDPE containers (thermoTabs), Multilayer Nylon Pouches etc. to suit industry’s requirements. With the availability of such innovative products both industrialists and regulators should work towards defining and harmonizing best practices.

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