Safety and tolerability of an oral zonisamide loading dose

AbstractPurposeThere are a limited number of anticonvulsant medications that can be administered with an oral loading dose in order to rapidly achieve an effective serum level, and most of these have associated adverse effects. Zonisamide is approved for the treatment of partial onset epilepsy, and is used in practice for both generalized and partial onset epilepsy. It is generally well-tolerated, has a long half-life, and can be administered once daily. Unfortunately, the recommended titration schedule for initiating therapy takes several weeks to reach target dose and therapeutic serum levels.MethodsWe initiated zonisamide therapy using a large initial dose of zonisamide in 32 patients in our epilepsy monitoring unit over the past four years.ResultsAdverse effects were rare and involved nausea/vomiting (9.4%) or drowsiness (6.3%). In patients where serum levels were available for review, therapeutic or near-therapeutic levels were achieved after an oral load of 600–900mg given as divided doses over a 6–12h period.ConclusionThis report is the first to suggest a method of rapidly initiating zonisamide therapy, achieving therapeutic serum levels in a shorter time frame, with an adverse effect profile similar to the recommended titration schedule

Paradoxical worsening of seizure activity with pregabalin in an adult with isodicentric 15 (IDIC-15) syndrome involving duplications of the GABRB3, GABRA5 and GABRG3 genes

Background: Isodicentric 15 syndrome (IDIC-15) is due to partial duplications of chromosome 15 that may includes the q11–13 region that includes genes encoding the α5 (GABRA5) and β3 - γ3 (GABRB3) receptor subunits. The disease causes intellectual and physical developmental delay, seizures, intellectual disability and behavioral disorders that may be related to abnormal GABA receptor function and morphology. Seizures are often severe and may be refractory to treatment. There are however no specific guidelines for the treatment of the seizures and it is unknown whether drugs that affect the GABAergic system have a different effect in IDIC-15 seizures. Case presentation: We report the case of an adult individual with IDIC-15 whose complex-partial seizures worsened dramatically after the introduction of pregabalin, with increased seizure frequency, frequent generalization, and appearance of new seizure pattern. Her cognitive function and verbal skills also worsened during treatment with pregabalin. Her seizures and cognitive skills quickly improved after pregabalin was discontinued and treatment with lacosamide started. Conclusion: As her genetic testing confirmed that her region of duplication included GABA receptor encoding genes, it is plausible that the worsening of seizures were due to induction of an abnormal GABAergic response to pregabalin.This case may help define proper therapeutic strategies for the treatment of IDIC-15 associated seizures