They recommend Benadryl for taking them on planes if they get a bit hyper in their carrier.
I took my 1 yr old to Atlanta in the car with no sedatives…she slept 80% of the way and did her business at rest stops along with me. I should mention she is one of the most well behaved animals I have ever seen so I had no reason to worry about it. But call the Vet and ask how much Benadryl to give a dog of that size and weight.