I see that you have already replied regarding niacin. Sorry for the duplication. I have however read an interesting article that suggests that Niacin flush actually modulates PGD2 here http://www.life-enhancement.com/magazine/article/3416-niacin-flush-protects-against-inflammatory-diseases
PGD2 only exists for half an hour so this makes no sense at all. You can't remove it like that. Unless you care about those 30 minutes.