Hi. I'm Dr. Lee and will do my best to help.
How far do your cats need to travel in the car?
Hello? Are you still there?
It looks like you are offline. I will switch to regular Q&A session.
Hi. If you can please give me more information as requested above so I can better understand the situation and help. Thanks.
It could be any where from 2 to 8 hours. Right now we're not sure,
Thanks for the info.
Ideally, you should get some prescription drugs from your vet, such as acepromazine. However, if you are looking for OTC drugs, you can try human Benadryl. You can get the 25 mg tablet and give 1/2 tablet. The problem with OTC is that it might or might not work as they are not true sedatives. You are welcomed to try Benadryl and see if that helps. If not, then you will have to ask your vet for prescription drugs.
Please let me know if you have any questions or concerns. Thanks.