Duloxetine may enhance control of pain related to bladder trauma

To the Editor

Duloxetine is a serotonin-norepinephrine reuptake inhibitor antidepressant (Bymaster et al., 2001), which also plays a significant role in the treatment of diabetic neuropathic pain (Bymaster et al., 2005). Here we report a patient with severe pain secondary to bladder trauma who responded to duloxetine as an adjunctive treatment.

A 23 year-old single male involved in a car accident two years previously experienced persistent severe pelvic injury, even after successive operations, including urinary bladder repair, urethral reconstruction, suprapubic cystostomy and malecot catheter placement. During the following two years the intermittent pain, lasting about 15 minutes per bladder contraction, with intervals of 30 minutes to two hours, responded poorly to oral gabapentin 100mg tid and solifenacin 5mg QD, even with adjunctive nalbuphine 10mg intravenously 3-4 times a day and ranged from 9 to 10 on self-rating as ‘severe and unable to endure’ using a visual analgesic scale (VAS).

A psychiatric consultation was requested because of a depressed mood for nearly two months, related to the unremitting pain. Loss of interest, difficulty initiating sleep, decreased energy, worthlessness and suicidal ideation were also present. A diagnosis of major depressive disorder was made, and duloxetine 30-60mg/day was commenced. On days two to three of duloxetine use, although the pain frequency and depression remained unchanged, the severity decreased from VAS 9-10 to 4-5. Ability to move from the bed was regained. Light activities outside the ward room were attempted, while his depressive mood, as well as his pain, improved during the following eight weeks.

In this case, there is little response when the pain management begins with gabapentin, nalbuphine and solifenacin, but prominent improvement after duloxetine administration. The observation that the pain preceded the depressive episode, and rapidly reduced after the administration of duloxetine, suggests that duloxetine possibly relieved the pain via analgesic pathways, rather than an antidepressant effect, which usually takes many weeks.

We hypothesise that duloxetine alleviates pain through simultaneous modulation of norepinephrine and serotonin in the descending analgesic pathway, from the supraspinal or spinal levels. Indeed, a recent study shows that duloxetine may block the NMDA receptor involved in pain perception in mice (Zomkowski et al., 2012).

To our knowledge, this is the first report of duloxetine use in the management of refractory pain from bladder trauma. Further studies are warranted to investigate the use of duloxetine in the management of pain from bladder or other pelvic trauma.