I'm new here and haven't followed the board, but why not just increase the oral dose of methotrexate? As far as I know, it does not cause GI side effects?
Bioavailability plateaus between 12.5 and 15mg with oral mtx. Diarrhea, nausea, and vomitting increases with dose.
Because higher doses will cause chemotherapy type side effects.
Duh? It's because over 15mg there is no additional benefit it just passes through.