I tried(just this morning) the fresh squeezed ruby red grapefruit by tropicana - did not seem to extend my on time however i did feel a faster onset however i did not take the fava juice - so far fava juice and quercitin are helping me extend that time to 6 hours/pill. (I take usually 2 doses/ day, 1 pill of either 25/100 OR 10/100 generic sinemet) will stay with the grapefruit juice and give it a chance to see. thanks for the thread Ron. my "offs" and "ons" don't really have clear boundaries so its a bit hard to make an immediate assessment

md