The only pure form of DXM that's OTC that I know of is Delsym, and it uses a plastic polistyrex for a "12 hour time release" instead of the "instant release" Hydrobromide (HBr) version that's found in most of the tablet versions, be ware that it's often compounded with other drugs to avoid the abuse of the DXM, so if you aren't taking pure DXM then you could be putting yourself at much higher risk of health complications.
Delsym is a syrup I forget I think it might be like 30mg/5mL, but if you to convert Delsym into the instant release kind (so you dont like... drink a whole bottle not knowing its time released and trip for days straight unintentionally) which can be done via performing a search on our database, I roughly recall it involving citric acid, I dunno, I have never found any appeal in abusing DXM, I don't even take it when I'm sick.
They make prescription pure DXM instant release, but I'm not allowed to tell you how to obtain that as that constitutes sourcing.
Anyways this threads in violation of forum guidelines, read the BLUA and OD guidelines before posting again, they're in my signature, k thanks!