In some guidelines, which antidepressant is used off-label to treat stress urinary incontinence by increasing urethral sphincter tone?

• A. Duloxetine
• B. Amitriptyline
• C. Fluoxetine
• D. Sertraline

Answer: (A)

Duloxetine works as a serotonin-norepinephrine reuptake inhibitor that boosts the signaling to the sacral spinal cord circuits controlling the external urethral sphincter. By increasing serotonin and norepinephrine in Onuf’s nucleus, it strengthens the sphincter’s tonic contraction, helping to prevent leakage during activities that raise abdominal pressure. In guidelines, this off-label use is noted for stress urinary incontinence because of this mechanism.

The other antidepressants listed don’t reliably produce the same effect on urethral sphincter tone. SSRIs like fluoxetine or sertraline, and the TCA amitriptyline, lack evidence of consistently improving stress incontinence through sphincter reinforcement, so they aren’t chosen for this purpose.