Introduction and hypothesis: Intravesical instillation of hyaluronic acid (HA) may restore the integrity of glycosaminoglycan layer in patients with painful bladder syndrome/interstitial cystitis (PBS/IC), and the benefit may be improved with addition of alkalinized lidocaine (AL).

Methods: 48 women with severe PBS/IC who failed oral medications were enrolled and divided into one trial and two control groups. The trial group received intravesical 40 mg HA, 10 ml of 2 % lidocaine and 5 ml of 8.4 % sodium bicarbonate on a weekly basis for 8 weeks and then monthly for 4 months with a subsequent follow-up of 24 weeks, while the two control groups received 40 mg HA and mixture of 10 ml of 2 % lidocaine and 5 ml of 8.4%sodium bicarbonate respectively following the same procedure. Response to therapy was evaluated by Global Response Assessment, voids per day, Visual Analogue Scale for pain, frequency and urgency, O'leary-Sant Interstitial Cystitis Symptom Index and Problem Index, cystoscopy and bladder capacity.

Results: Overall 45 patients finished this study protocol. The HA + AL group and the AL group showed significant improvement at week 2 (P < 0.01), while the HA group began to show effect at week 4 (P < 0.01). There was no improvement in the AL group at week 24 and these patients quitted the study without follow up. Contrarily, the HA + AL and HA group kept on improving till the end of the study without significant difference between the two groups.

Conclusions: Intravesical instillation of HA and AL may provide both immediate and sustained relief of symptoms in severe PBS/IC in this preliminary study.