Epipen are very good at marketing, short shelf life efc. I would suggest that the advise would be due to the plastic mechanism failing, not break down of the drug inside. Our Ambo drugs are constantly in the van and we have no issues. Maybe discuss with your Doc getting a script for an ampule of adrenaline, and learning to draw it up yourself? ( not rocket science) and you get a better does, 2x 0.5mg compared to 0.3mg.
An ampule costs about about $4 compared to $150 epipen.
Don't be scared of of messing up, remember adrenaline is a naturally occurring hormone so no contra-indications and so it is very unlikely to get negative effects with one vial.
The paper below did research in storage of ALS Drugs in hot cars, adrenaline/epinephrine included. They found they do not deteriorate with heat.
Results: Seven sites exceeded 104 ?F (40 ?C) for as little as 30 minutes and as long as 795 minutes. Ten of the sites achieved a mean kinetic temperature (MKT) above 77 ?F (25 ?C), with the highest MKT calculated being 84.1 ?F (28.9 ?C) over a 45-day period. There was no evidence of drug degradation at any site, at any temperature, or at any time point.www.medscape.com/viewarticle/472699