Probability of rash related to gabapentin therapy in a child

To describe a child who developed a skin reaction during gabapentin therapy and discuss how we evaluated the probability of an adverse drug reaction.

An 8-year-old boy with a neurodegenerative disease of unknown origin and an epilepsy disorder developed an urticarial rash and irritability 10 and 4 days, respectively, after the start of gabapentin 20 mg/kg 3 times a day for epilepsy control. Otherwise, the child was well; no changes in other medication or diet had recently been made. After gabapentin discontinuation and administration of one dose of methylprednisolone 10 mg/kg intravenously and diphenhydramine 1 mg/kg every 4 hours via gastric tube, the rash disappeared over 3 weeks.

In contrast to other antiepileptic drugs, skin reactions to gabapentin are considered uncommon. In adults, reported prevalence of rash possibly related to gabapentin range from 1% to 10%. A postmarketing surveillance study reported gabapentin treatment failure as a consequence of rash in 0.4% of 3000 patients. The product monograph does not mention rash in children. In our patient, assessment using an objective causality scale revealed that the rash was probably caused by gabapentin.

This case, and limited literature data, suggest that gabapentin may cause rash that is severe enough to necessitate discontinuation in a small percentage of children. Further research is needed to determine the actual incidence and severity of gabapentin-related rash in this population.