There is little info online about homatropine, but it is Related to, and less potent than atropine apparently. It's put in syrup to aid in bronchial secretion for cough, and secondarily as a deterrent to abuse. I've experienced 50 mg hydrocodone/15 mg homatropine doses without incident. I don't recall any negatives from the homatropine. I notice other posts on other forums that pin it at no more than 15 mg max. So it seems there is some agreement across boards for your question. Which is about the best you are gonna get on this I think unless a physician or someone with hard pharmacological knowledge chimes in. Have fun. I like that stuff. Not as good as Tussionex, but it works.