Abstracts

Side effects are one of the leading limiting factors in the use of anticonvulsant medications. A rash is a known side effect of lamotrigine. However, there is not much information available regarding the relationship between lamotrigine and late onset rash. Is the rash likely to be due to lamotrigine and does it necessitate discontinuation of the medication especially if the medication is effective?, This is a prospective and retrospective case series study evaluating the patients in the Epilepsy Clinic. Pertinent clinical information was collected through a chart review. Patients with onset of rash and on lamotrigine therapy were identified. Late onset rash was defined as rash occurring greater than six months after the initiation of lamotrigine therapy. Patients were evaluated by a Dermatologist or a Primary Care Physician to determine the cause of the rash., There were seven patients identified. The time to onset of rash from initiation of lamotrigine therapy ranged from 9 to 71 months (mean 28.6 months, median 18 months). Four out of the seven patients were on lamotrigine monotherapy with the rest being on polytherapy in combination with different anticonvulsant medications with none however including valproic acid. Two had a diffuse rash with the rest being localized. In three of the patients including the two with the diffuse rash lamotrigine was stopped without resolution of the rash. With the discontinuation of lamotrigine, the majority of these patients experienced an increase in their seizure frequency requiring the reinitiation of lamotrigine therapy once it was determined that the rash was due to another cause. In all the patients that the lamotrigine was continued there was no worsening of the rash or any other medical complications. In all of the cases the cause of the rash was determined to be something other than a lamotrigine induced rash with the most common causes being eczema and cosmetic reaction., Late onset rash in patients taking lamotrigine is not an uncommon occurrence. However, in our case series none of the rashes were determined to be due to lamotrigine. If the rash is severe it is prudent to stop the lamotrigine, but patients should be evaluated to accurately determine the cause of the rash especially if the medication is effective in controlling their seizures. Furthermore, if the rash is limited and the patients are doing well on this medication consideration should be given to continuing the lamotrigine during the evaluation process.,