Storage temperatures of out-of-hospital medications

To determine whether temperatures inside drug boxes used in the out-of-hospital setting are within the U.S. Pharmacopeia recommendations for "controlled room temperature," which is defined as a temperature maintained between 15 degrees C and 30 degrees C with a mean kinetic temperature less than 25 degrees C, and to determine whether time-temperature indicator labels can reliably monitor mean kinetic temperatures.

Two methods were used to monitor temperatures: miniature electronic temperature recorders and color-changing time-temperature indicator labels. These were placed in drug storage boxes of advanced life support units over three summer months and two winter months.

In summer, the electronic recorders logged temperatures exceeding 30 degrees C in all drug storage boxes, ranging from 3% to 29% of the total time. The mean kinetic temperatures by location for the whole period ranged from 21 degrees C to 30 degrees C. In the winter, the electronic recorders logged temperatures exceeding 30 degrees C at one location 2% of the total time. There were significant temperature excursions below 15 degrees C at all locations, ranging from 16% to 90% of the total time. At one location, there were temperature readings below 0 degrees C for 9% of the total time. The mean kinetic temperatures obtained from the electronic recorders and the indicator labels differed by less than 1 degrees C.

This study demonstrates that out-of-hospital medications are subject to temperatures both above and below recommended storage temperatures. Time-temperature indicator labels can reliably monitor exposure to elevated temperatures.