On their last stage to the study site, temperature-sensitive clinical trial material is mostly transported in passive coolers. Passive coolers are equipped with cold packs or cooling pads to keep the cargo cool during transportation. Before that, they were transported from one country to another in large, actively cooled containers, passed several national borders and crossed various climatic zones. In the logistics hubs they are then prepared in small volumes for transport on the last mile.
Passive coolers: disposable and reusable
For the transport on the last mile, passive cooling boxes are currently most frequently used. Depending on the quality, they are one-way or reusable coolers. The latter means that they last for a maximum of 5-7 transportation cycles before they have to be disposed of. They are usually tampered with by the transports, so that they no longer a presentable to a customer. The difficulty of the reusable boxes is furthermore that, due to the appearance of the boxes, the addressees are not always aware of the fact that they it is a reusable cooler. This is why many people throw it away, even though they could still be used.
Both disposable and reusable passive coolers must be prepared in advance in order to ensure refrigeration for transport. The recharge time for the cold packs is 12 to 72 hours depending on the cooling requirements. An adhoc transport is thus not possible.
The passive coolers are done … what now?
In the case of disposable coolers, one and a half tonnes of garbage are thrown away for 1 liter of transported goods. In the case of cartons, which are equipped with cold packs, the former are relatively easy to dispose of. However, if transport boxes are made of polystyrene or similar material, disposal is costly. Polystyrene is made of petroleum with a high energy consumption and can be disposed of only with difficulty in the landfills, since high combustion temperatures are necessary for this material. In terms of environmental compatibility, the material is critical, since toxic gases are produced during combustion.
There are many manufacturers of such boxes and the list prices for these vary greatly. From 300 € for a disposable cooler up to almost 2000 € for a reusable one everything is represented. This is why the limited lifetime of these passive cooling solutions comes as a high cost factor. The cost of the necessary equipment ads to the purchase or rental costs of the coolers. In clinical trials monitoring temperature, humidity and location plays an increasingly important role (see Temperature logger). Sponsors and logistics service providers have a great interest in closely monitoring the transport of temperature-sensitive and high-priced freight. Disposable temperature loggers cost an additional € 40 – only for temperature measurement. If more data is to be tracked, this price increases quickly by several hundred euros.
As a conclusion, passive coolers are useful for cost reasons where the freight is of little value or the return of the boxes is difficult. This is not the case for logistics in clinical trials.