5-Aminolevulinic acid (5-ALA) reportedly improves overactive bladder (OAB) symptoms by reducing reactive oxygen species derived from vascular endothelial cells to protect vascular function and enhance bladder blood flow and by inhibiting bladder C-fiber activity. This double-blind, randomized controlled trial aimed to evaluate the efficacy and safety of 5-ALA in participants with OAB.
This randomized, prospective study classified the participants into the 5-ALA and placebo groups. The 5-ALA group received oral 5-ALA phosphate at 150 mg/day for 12 weeks. The efficacy of 5-ALA was determined by assessing the changes in the Overactive Bladder Symptom Score (OABSS) and the Overactive Bladder Questionnaire Short Form from baseline to weeks 4 and 12 after treatment initiation, as well as the post-void residual urine volume. Regarding safety, we evaluated participants' blood pressure and adverse events.
This study enrolled and randomized 49 participants, with 23 in the 5-ALA group and 26 in the placebo group. Ultimately, 47 participants completed the study (21 and 26 in the 5-ALA and placebo groups, respectively). From baseline to week 12, OABSS significantly decreased from 8.81 to 6.52 (- 2.29) in the 5-ALA group and from 8.54 to 6.35 (- 2.35) in the placebo group (both: p = 0.008). However, no significant difference was noted between the two groups at week 12 (p = 0.956). Using a mixed model for repeated measures with a random intercept, the model-adjusted between-group difference in the change from baseline to week 12 in the OABSS between the 5-ALA and placebo groups was 0.06 points (95% confidence interval, - 1.63 to 1.75; p = 0.944).
This study found no significant improvement in OAB symptoms with 5-ALA administration. Nevertheless, given that no previous double-blind, randomized controlled trial has assessed 5-ALA's efficacy in patients with OAB, this study holds important value as a pilot study.
This study was prospectively registered in the Japan Registry of Clinical Trials (jRCT); registration number: jRCTs061220050; registration date: [August 29, 2022].
European journal of medical research. 2026 Feb 20 [Epub ahead of print]
Satoshi Fukata, Nobutaka Shimizu, Takahira Kuno, Rie Yoshimura, Hiroki Sugimoto, Ayano Kawaguchi, Yoshitaka Kurano, Daigo Takemori, Shinkuro Yamamoto, Taeko Nishioka, Natsuko Nakamura, Hajime Kuroiwa, Hiroko Iijima, Takashi Karashima, Keiji Inoue
Department of Urology, Kochi Medical School, Kochi University, Nankoku, Kochi, 783-8505, Japan., Pelvic Floor Center, Kochi Medical School, Kochi University, Nankoku, Kochi, 783-8505, Japan. ., Department of Urology, Tosa Municipal Hospital, Tosa, Kochi, 781-1101, Japan., Department of Urology, Hata Kenmin Hospital, Sukumo, Kochi, 788-0785, Japan., Integrated Center for Advanced Medical Technologies (ICAM-Tech), Kochi Medical School, Nankoku, Kochi, 783-8505, Japan.