Purpose: Urinary nitric oxide synthase activity is decreased in patients with interstitial cystitis. Since nitric oxide may be an important determinant of the symptoms and immunological responses associated with interstitial cystitis, patients with this disease were treated with oral L-arginine, the substrate for nitric oxide synthase.
Materials and methods: Ten patients took 1.5 gm. L-arginine orally daily for 6 months. Interstitial cystitis symptoms were surveyed before and during the 6-month trial.
Results: Oral L-arginine treatment resulted in a significant decrease in urinary voiding discomfort, lower abdominal pain and vaginal/urethral pain. Urinary frequency during the day and night also significantly decreased.
Conclusions: This self-controlled study provides evidence that long-term oral L-arginine improves interstitial cystitis related symptoms.