Here is a discussion in http://www.rosaceagroup.org/The_Rosacea_Forum/showthread.php?21929-Ivermectin-for-Demodex about applying a horse OTC product containing ivermectin, topically.
More info:
https://rosacea-support.org/ivermectin-clears-untreatable-rosacea.html
http://www.amazon.com/Horse-Health-Ivermectin-Dewormer-Paste/dp/B003NTOI76
(Note that I don’t know whether it is safe to use this without precaution.)