The Risky Business of Transporting Drugs in the TropicsThe Risky Business of Transporting Drugs in the Tropics

The United States Pharmacopeia (USP) has issued a pre-posting notice regarding the anticipated publication of General Chapter <1079.2> in USP-NF 2025, Issue 2. The chapter outlines the use of mean kinetic temperature (MKT) to evaluate temperature excursions during the storage and transportation of pharmaceutical products.

The chapter currently includes temperature excursion limits for Climatic Zone II, which covers products stored at controlled room temperature (20 – 25º Celsius) and at controlled cool temperature (2 – 8ºC). The chapter does not consider product storage between 15 and 30ºC, which is generally the storage and transportation range for drug products in Climatic Zone IVb countries. As a result, the revised chapter will add temperature excursion limits for Climatic Zone IVb.

What is MKT?

A stimuli article, titled The Use of Mean Kinetic Temperature and the Need for Allowable Excursion Limits for Climatic Zone IVb, defines MKT as “a single calculated temperature at which the total amount of degradation during a given period is equal to the sum of the individual degradations that would occur at various temperatures.”

Although MKT is used to assess temperature excursions, it is not enough by itself. It is also necessary to know the duration of the temperature excursion; the actual excursion temperature; if there was a temperature excursion above 40ºC; and the timeframe used to calculate MKT.

Why the revision?

According to the stimuli abstract, there is a growing concern about the proper storage and transportation of finished drug products because storing and transporting them outside of their storage specifications can potentially impact product quality, efficacy, and safety. Although every effort should be made to keep the drug within the temperature range indicated on the packaging, temperature excursions can occur.

In Climatic Zone IVb, drug products whose stability studies were conducted to provide storage from 15 to 30ºC are often transported in non-temperature–controlled vehicles that can go through various temperature extremes during a journey or are stored at in-transit storage facilities that do not have thermostatic control of temperature.

The suggested updates for temperature excursion limits for Climatic Zone IVb can help supply chain stakeholders decide whether to keep or discard a product after excursion.