Back when Motrin first came out the Powerlifters used it daily and where always bugged by the commercials which pushed it as a PMS ibu...
Anyhow, just compare the size of the pill to any other similar strength ibu and you can tell they added other stuff for delivery. Just like TCM does, they always add other herbs to help the delivery of drugs.
Of course I don't know for sure but there is a huge difference between ibu drugs...
BTW: I still have a bottle and used the first pill in three years the other day. The rest of the time MSM and Curcumin•95 is all I need. That said; wasn't using it for PMS...