Evaluating temperature excursions in transport

When a logger shows an out-of-range value at the end of a journey, the first instinct is often to ask whether the product is spoiled. That question is not answered on the dock or in the truck. The data is collected first, the goods are put on hold, and the decision is left to the party that knows the product’s stability.

What does GDP ask of transport?

Chapter 9 of the EU GDP guidelines covers transportation. Its main expectations are these:

• Throughout transport, the product stays within the limits set by the manufacturer or shown on the outer packaging.
• If there is a temperature excursion or damage, it is reported to the distributor and to the recipient of the affected products.
• A written procedure describes how excursions are investigated and handled.
• Temperature-sensitive products travel with qualified equipment: thermal packaging or temperature-controlled vehicles.
• Monitoring equipment in those vehicles is maintained and calibrated.

How is an excursion evaluated?

The evaluation runs in a few steps:

1. The goods are quarantined. Until a decision is made, they wait in a separate area and are blocked in the system.
2. The logger data for the whole journey is collected. The full record from loading to delivery is needed, not only the moment of the excursion.
3. The size of the excursion is established: how far did the temperature leave the range, and for how long?
4. The data and a description of the event go to the product owner, meaning the manufacturer or the marketing authorisation holder.
5. The product owner decides whether the product can be used, based on its stability data.

Until that decision, the goods are neither shipped nor destroyed. Neither the warehouse nor the carrier makes the call alone.

What is mean kinetic temperature (MKT)?

Temperature in transport is rarely steady. It rises and falls, and sometimes leaves the range for a short while. Mean kinetic temperature (MKT) expresses the combined effect of such a varying temperature history as one equivalent temperature. Because the rate of degradation rises with temperature, the calculation gives warm periods more weight than a simple average would.

USP General Chapter <1079.2> describes how MKT can be used in evaluating excursions.

MKT is a tool for the product owner’s assessment. It is not permission to ignore an excursion. Whatever value the calculation gives, the excursion is still recorded and investigated, and the decision still rests with the product owner.

Preventing excursions

Evaluation happens after an excursion; prevention happens before. Most excursions occur at handovers: waiting on the dock, loading, and every door opening on a multi-drop route. We cover these points in Where does the cold chain break? To see temperature differences inside the warehouse itself, the tool is temperature mapping.