To add to this aspect:
Pandas are especially prone to reject conventional therapy, because therapy is a demand: "Healing begins now".
Same thing goes with medication: "We expect you to get better after taking this"
For myself, the best thing is to just let me do my thing. Put the meds somewhere where I can see them. But don't expect me to take them. If they'll help and you're away, I may decide I take them, but because I want to, not because it's expected from me.
But that also means: If I myself feel better without the meds, I won't take them.
(but I'm a high masking late diagnosed panda and in regards to PDA/ADHD unmedicated, therefore I have no expertise with medications of panda-children or how parents would handle that.)