Anticholinergic/sedative combos decreases levels of promethazine by inhibition of GI absorption. Applies only to oral type of both brokers. Use Caution/Monitor. promethazine decreases effects of pitolisant by Other (see comment). Stay clear of or Use Alternate Drug. Remark: Pitolisant improves histamine levels while in the brain; as a result, H1 https://wockusa.com/product/1b-lsd/