Urovant Sciences Ltd.'s stock dipped by over 18% following news that its medicine vibegron helped patients with overactive bladder but not significantly so when compared to a generic drug.

Urovant stocks were down 18.18% to $11.38 per share as of 1:23 p.m. on March 19, 2019.

The London-based biopharmaceutical company evaluated vibegron against placebo and another drug called tolterodine in a phase 3 trial dubbed Empowur, which included 1,518 patients with symptoms of overactive bladder.

After 12 weeks of treatment, patients receiving the 75-milligram dosage of vibegron showed statistical significance in reducing the daily instances of an urge to urinate — which is followed by an involuntary loss of urine — and a reduction in daily micturitions, or number of times a person urinates, when compared to placebo. Specifically, patients saw an improvement of 2 and 1.8 in incontinence and micturition, respectively, compared to 1.4 and 1.3 for placebo.

Patients who received tolterodine saw an improvement of 1.8 and 1.6 in incontinence and micturition, close to the improvements of vibegron.

The trial also met seven secondary goals, which included a statistically significant reduction in daily urgency episodes when compared to placebo.

Vibegron was well-tolerated during the study. Urovant plans to file for a U.S. approval of the drug by 2020, the company said in a March 19 press release.

Once approved, the drug would compete with Astellas Pharma Inc.'s overactive bladder therapy Myrbetriq. According to Fierce Pharma, Urovant believes its medicine is safer and provides quicker relief than Myrbetriq.