Okay Spoilers Need here please! A drug called Switch?

Yes. Can switch alpha to omega and omega to alpha, but it only switch the body response temporarily, the actual trait remains

So the Uke used that drug and still have sex with the Seme by being both Omega and Alpha?

It’s alpha x alpha. Uke, the one who really love seme for years, use the drugs to switch the body reaction to look like male omega so it will be less unpleasant for seme, but still… the seme has strong dislike of having male partner anyway… so you can guess how seme treat the uke

Ohh No, thanks