Duloxetine is used off-label to treat stress incontinence by increasing urethral sphincter tone.

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

Answer: (A)

Duloxetine works for stress incontinence because it increases serotonin and norepinephrine in the neural pathways that control the external urethral sphincter. By boosting these neurotransmitters in the Onuf’s nucleus of the sacral spinal cord, it enhances reflexive contraction of the sphincter during moments of increased abdominal pressure, improving outlet closure and reducing leakage. This specific effect on sphincter tone is why duloxetine is noted for this off-label use. The other antidepressants primarily affect mood and do not reliably increase urethral sphincter tone through the same pathway, so they’re not used for stress incontinence for this purpose.