Intravesical tacrolimus in treatment of intractable interstitial cystitis/bladder pain syndrome - A pilot study

Aims Interstitial cystitis/Bladder pain syndrome (IC/BPS) is a chronic condition with limited effectiveness of current treatments without any cure. Cyclosporine A is effective in intractable cases of BPS/IC. Tacrolimus has same mechanism of action. The purpose of this pilot study was to find if tacrolimus instilled in bladder is effective in treating BPS/IC without side effects. Methods From February 2013 till Dec. 2017 tacrolimus dissolved in DMSO/sterile water was instilled in bladder of 24 patients of intractable BPS/IC. Patients received one to six cycles of therapy at interval of 14 days. Base line complete blood count, blood glucose, renal and liver function test were done and repeated after every three instillations. Serum tacrolimus level was also measured in 10 patients. Primary study endpoint was Global Response Assessment (GRA) score. Results 13 out of 24 patients showed improvement in a follow up extending from 6 to 63 month. Except for post- instillation flare in symptoms no side effects were observed in the patients during follow-up. Blood levels of tacrolimus reach same safe level irrespective of using either DMSO or water for preparing the solution. Conclusions Intravesical tacrolimus dissolved in DMSO/water has been found effective in 54% patients of intractable BPS/IC without significant side effects in this pilot study. For the first time we have discovered that though tacrolimus is believed to be insoluble in water it gets absorbed by bladder urothelium when a solution of tacrolimus in water is instilled in urinary bladder. It should be offered to the patients before offering surgery.