If you are looking for the anti oxidant effect the studies were done with oral dosing that I read. It's an interesting question. I don't know how old you are (I'm old) but I read that if you aren't over 40 you really don't need to do the GlyNac thing because Glutathione is high enough untill the 40's. I take gycine (in the form of collogen peptides) twice a day, but I only take the NAC at night becausre it is my understanding that SOME oxidive stress is actually good for cells.