This long lasting reusable gel ice pack for medicines stays cool for a good 8 hours or longer depending on the temperature it is being exposed to and how long etc..
 
Durable Nylon exteriorFreeze 2-3 hours prior to useAccording to our test data this ice pack can stay cool at least 8 hours when the ambient temperatures were 23-25℃ / 73.4 – 77℉
 
Large Size: Measure 4" x 7.5"