If he doesn't need an injection during the flight, as its only once a week then he could pack them in his hold luggage. However, if he's anxious about loss of luggage then I'd suggest he gets a doctors letter and also inform the airline before departure.

I also need to take injections with me and have done for the last 2 years without problems,inform your airline that you are carrying them and if like me he has to keep them cool just take a doctors letter,got mine from healthcare at home who supply the jabs, just carry seperately from hand luggage and tell them at check in and at security so thy can hand check them and not x ray them.hope this helps

Thanks guys

Whan taking a child who needs an epipen on a plane I needed a letter from his doctor to confirm he needed it and they checked it at security to make sure it was what it said on the box.

I am waiting on letter from Doc, hope to get it before Thursday.