Low does naltrexone works very well for IC. It is an FDA approved drug at 50 mg/day, but was found in the 1980's to work at very low doses of 1.5-4.5mg/day, taken at night, to put into remission many autoimmune disease, MS, Crohn's and many more illnesses. It is non-toxic, no side effects (except possible sleep disturbances for a week or two, in which case it can be taken in the morning) out of patent so very inexpensive drug used by thousands. Here are reports from users for IC:
Find the site at www.ldninfo.org and join the Yahoo Group at the top part of the page. It has over 13,000 members who take LDN, and they are very helpful in answering any questions you may have. Best wishes to feel better!