How many days worth of medicine do you need to carry?
I ask because last year, the supplier would always deliver my peginterferon in thermocol storage boxes, with ice-packs in it. I was told that as long as I keep the box sealed, it will last up to a week. Of course, you would not use ice-packs for 25C, but still, a thermocol box would be quite suitable for your task. The one I used was huge (approx 25cm x 20cm x 20cm) but I suppose you can find them in all kinds of shapes and sizes. If you go to a drug supplier, they might even give you one for free.
You might want to use something like http://www.dataclean.com/temperature_strips.htm on the inside. I do not know if the one I linked to is reusable - not the kind that locks down on the highest or lowest temperature it has ever seen.
thanks, i travel for 1-2 weeks with no electricity most of the time so it is not easy.
i guess a box like yours plus a mini fridge should work or a very small minifridge which works with batteries but until now i haven't found it