CYP3A4 and interstitial cystitis: SUI PVR > 200 ml Qmax < 10 ml/s Total urinary volume > 3 l/day Significant hepatic or renal disease UTI (symptomatic or recurrent) Interstitial cystitis or haematuria Recent electrostimulation or bladder training therapy Indwelling catheter or intermittent self-catheterisation Pregnancy, lactation, or failure by women of childbearing age to use reliable contraception Use of CYP3A4 inhibitors Treatment within 2 weeks of study with OAB therapy or anticholinergic drugs