How do I know if it’s okay to use Zylkene for my cat?

Hi, I have a cat that I have not managed to convince to ride in a transport cage.

I have tried to have Feliway in the cage, make it cozy and have it in front so that he can be in it even when there is no transport.

Have also tried to ride both car and train, in the car he does not scream so dangerously when the car is stationary and on the train it will be a little more okay as I can open the cage a little and scratch him on the stomach (this will be difficult if there are other animals in the carriage).

Otherwise he screams a lot and sometimes he pees, so we prefer to avoid travel.

Now, however, we will move to a new city, which will take about 2-3 hours.

Of course, I want it to be possible without him becoming unnecessarily difficult to deal with.

What I wonder is if it is likely that he is motion sick or panicking about the situation?

Have you thought about Zylkene which I read can be soothing, does it require a veterinary examination?

My cat is 10 years old and has no health problems as far as I know (last vet visit was a few months ago).

Do you have any other tips on how I can facilitate the move for him?

Any advice is appreciated!