FDA Approves First Fast-Acting Drug for Clinical Depression, Works in 1 Week
prevention.com
prevention.com
So maybe this is supposed to be a scattershot to try two things that might work. If it comes back after a week without, it was the BUP that worked, otherwise the DXM.
your best bet is getting a compounding pharmacy to make the tablets for you, if your insurance doesn't cover this and it's too expensive out-of-pocket.