The UK Government has published a list of compounds that will move from being regulated under the Psychoactive Substances Act to the Misuse of Drugs Act. (you can check the original legislation on the UK gov website if you wish, I am wary to link it here for security reasons).
When the legislation is passed (this is likely to happen around June) these compounds will become as illegal to possess as “normal drugs” (previously it was only an offence to sell or try and import them).
They will get the classifications listed below:
Isopropylphenidate (IPP or IPPD)