Gabapentin-Induced Overflow Urinary Incontinence: A Case Report and Review of the Literature.

Gabapentin (GBP) is a structural analog of gamma-aminobutyric acid (GABA) that is commonly used in palliative care for symptom management indications including neuropathic pain syndromes, hiccups, cough, and anxiety. An uncommon adverse effect of GBP is urinary incontinence (UI). We report the case of a 61-year-old male with metastatic non-small cell lung cancer who developed probable overflow UI while receiving 1200 mg/day of GBP for chemotherapy-induced peripheral neuropathy. The patient self-tapered GBP to 600 mg/day which resolved the overflow UI, but resulted in poorly controlled bilateral foot pain. The palliative care physician rotated the patient to pregabalin 150 mg/day and his bilateral foot pain improved after his regimen was titrated to 200 mg/day. The patient did not experience overflow UI while taking pregabalin despite the similar pharmacology and comparable doses to GBP. We believe this is the first case report to describe subsequent achievement of pain control by substituting pregabalin without recurrence of UI. Healthcare professionals should consider GBP as a potential cause when evaluating patients presenting with new onset overflow UI.