Serious and heavy pure music. Beethoven's "Moonlight Sonata" is quite heavy and serious, but I gave it a try, but it doesn't seem to be suitable for anti-drugs.

Bandari's "New Morning" has a more sedate melody. Dear, you can give it a try. It should be suitable for anti-drug use.

Bandari's "Snow Dream" is a piano-based song. You should have heard it.

Bandari's "Endless horizon" himself I think this song may be more suitable as the most anti-drug background music, but it also has a feeling of hope.

The above are my suggestions. In the end, it is up to you to decide. I just provide some songs. If you can't find something suitable here, you can continue to ask and I will find some more songs for you.