Abstracts

Rationale: Antiepileptic drugs (AEDs) are used in the treatment of epilepsy, pain, and psychiatric disorders. Renal status may impact the efficacy and toxicity associated with AEDs which requires awareness by clinicians in multiple specialties. Gabapentin is cleared solely by renal excretion and dosing requires consideration of the patient s renal function. We report 2 cases of myoclonic activity associated with gabapentin toxicity in the setting of renal disease and address treatment with dialysis.Methods: Case analysis with PubMed literature review was employed.Results: Case 1: 78-year-old woman with congestive heart failure, history of thromboembolism, hypertension, diabetes mellitus, asthma and diabetic peripheral neuropathy presented with tremors involving her upper extremities for 3 days prior to admission. Evaluation revealed acute kidney injury (AKI) secondary to increased furosemide and lisinopril with hyperkalemia and azotemia. The patient was noted to have severe myoclonus. Prior to admission, the patient was treated with gabapentin 900 mg total daily dose for neuropathic pain. The patient had no history of renal disease, but presented with an estimated glomerular filtration rate of 13 mL/min/1.73 m2. With discontinuation of gabapentin and initiation of hemodialysis (HD), marked improvement in her myoclonus occurred. Patient received 2 session of HD, and was discharged with normal renal function and resolved myoclonus. Gabapentin was held on discharge. Case 2: 55-year-old man with end-stage renal disease on peritoneal dialysis (PD), diabetes mellitus, hypertension, neuropathic pain, and peripheral vascular disease with toe gangrene on long term antibiotics presented for evaluation of diffuse body tremors, altered mental status and worsening leg infection. Gabapentin 600 mg total daily dose was initiated for neuropathic pain 3 days prior to presentation with myoclonus. The patient s PD treatment was increased from 4 to 6 exchanges daily. With increased dialysis and discontinuation of gabapentin, myoclonus resolved. Conclusions: Myoclonic activity may occur as a complication of gabapentin toxicity, especially in the setting of renal dysfunction. In the cases reported, both HD and PD were effective in treating myoclonic activity in acute and chronic renal dysfunction. Gabapentin requires renal dosing in patients with chronic kidney disease and in patients at risk for developing AKI. As gabapentin has multiple indications, an understanding of such renal dosing is important to clinicians in multiple specialties.