Mean Kinetic Temperature

What is the role of MKT in stability study

A single derived temperature that, if maintained over a defined period of time, affords the same thermal challenge to a drug substance or drug product as would be experienced over a range of both higher and lower temperatures for an equivalent defined period. The mean kinetic temperature is higher than the arithmetic mean temperature and takes into account the Arrhenius equation.

n the ICH guideline: “Stability Testing of New Drug Substances and Products Q1A(R2)” MKT is justified for use to represent a given thermal challenge to a product over a range of temperatures for an equivalent period because it is higher than the arithmetic mean temperature and takes into account the Arrhenius equation, making it a conservative value.

Based on the drug stability study presented by W. Grimm (1985, Drugs Made in West Germany), the WHO separates the world into major four climatic zones such as subtropical, temperate, hot/humid, and hot/dry. Rules cited in ICH Q1A(R2) are intended for climatic zones I-II (Japan, USA, and EU).

The ICH guideline asks us to use the climatic zones to assess choice of test conditions based on an analysis of the effects of climatic conditions in the three regions of the EC, Japan and the United States.

In uncontrolled pharmaceutical storage, climate-based temperature changes make it complex to choose one single temperature for testing the expiry or shelf life of products. The main aim of the 1971 Haynes paper was to deal with this climate-based temperature variation.

The rate at which product begins to degrade is governed by the variations in storage temperature. In order to deal with this variation, Haynes calculated a “Virtual Temperature” for application in expiry testing that would consider the variability of the predicted temperature in a specified area.