USP pre-posts Revision to General Chapter <1079.2> and Stimuli Article on Mean Kinetic Temperature (MKT)

The United States Pharmacopeia (USP) has published a Notice of Intent to Revise General Chapter <1079.2> Mean Kinetic Temperature in the Evaluation of Temperature Excursions During Storage and Transportation of Drug Products. With the revision, the inclusion of temperature excursion limits for climatic zone IVb is being proposed. In a Stimuli Article entitled "The Use of Mean Kinetic Temperature and the Need of Allowable Excursion Limits for Climatic Zone IVb", the rationale for the revision is outlined.

Both documents, the revised Chapter <1079.2> and the Stimuli Article, were pre-posted prior to their publication in the Pharmacopeial Forum (PF 49(2) in March 2023). According to the USP, this was to allow stakeholders additional time for reading and understanding.

Revision of General Chapter <1079.2>

USP General Chapter <1079.2> is part of the <1079> series of chapters on Good Storage and Distribution Practices. The current version (official as of 01 December 2020) addresses the utility and application of mean kinetic temperature (MKT) for the evaluation of temperature excursion in controlled room temperature (CRT, 20 - 25 °C) and controlled cold temperature (CCT, 2 - 8 °C) products. Thus, it contains temperature excursion for climactic zone II only.

Product storage between 15 and 30 °C, which is generally the storage and transportation range for drug products in climatic zone IVb countries, is not considered. Therefore, in the new draft, the inclusion of excursion limits for climatic zone IVb is being proposed.

The revisions concern subchapter 4 (Application of MKT), in particular. Table 1 was revised. It now presents the use of MKT and allowable temperature excursion limits for CCT, CRT, and room temperature in climatic zone IVb (15 - 30 °C). An explanatory text was inserted. It is noted that MKT should not be abused, as MKT alone is not enough to assess the impact of a temperature excursion. It is necessary, in addition to MKT, to know 

  • the time period of the temperature excursion,
  • the actual excursion temperature(s),
  • if there was a temperature excursion above 40°,
  • the time frame used to calculate MKT.

Stimuli Article

The authors write that "the aim of this Stimuli Article is to present the case for updating <1079.2> to address MKT for climatic zone IVb."

The introduction of the article reports about a GDP workshop in March 2022, organized by the USP Latin America (LATAM), in partnership with the Pharmaceutical Products Industry Companies Union and the Brazilian Academy of Pharmaceutical Sciences, two important stakeholders in Brazil. One of the outputs of the Q&A sessions was that it might be useful to update the USP MKT standard to accommodate storage and transportation of drug products in climatic zone IVb.

The Stimuli Article then gives an overview of the pharmaceutical supply chain and the risks related to temperature excursions, followed by a suggestion for allowable excursion limits for climatic zone IVb. The article ends with a conclusion, stating that "the temperature excursion limits for climatic zone IVb in this article that were suggested for updating <1079.2> can help supply chain stakeholders in the decision-making process as to whether to keep or discard a product after excursion."

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