One of the many possible side effects of antiepileptic drugs is a change in weight. Valproate, in particular, has been associated with weight gain. However, a recent study by Patricio Espinosa, MD, MPH, presented at the 58th Annual Meeting of the American Academy of Neurology, San Diego suggests that weight gain with valproate may be a problem for teenagers and adults, but not for children less than 12 years old.

Espinosa, a 3rd year neurology resident at the University of Kentucky, College of Medicine and Public Health, Lexington, KY, and his colleagues reviewed the charts of all children less than 12 years old taking either valproate or carbamazepine monotherapy that they saw in their clinic between 1984-2002. Thirty five children (77.4% males, mean age 9.3 years) took valproate and 49 children (40.8% males, mean age 7.15 years) took carbamazepine. Using two different statistical methods, only the children taking carbamazepine were found to gain weight. Since the children were expected to gain weight over time as they aged, both statistical tests were adjusted for normal weight gain due to growth.

Jack Pellock, M.D., Professor and Chair, Division of Child Neurology, Virginia Commonwealth University, Richmond, VA, commented, “These findings are interesting. There has been for a number of years a feeling amongst healthcare professionals that prepubertal children may have less weight gain from valproate than adolescents, where it becomes more obvious. A larger, better controlled study would surely be helpful to further clarify the issue.”

Angus Wilfong, M.D., Medical Director, Comprehensive Epilepsy Program, Texas Children’s Hospital, Houston, TX, agreed with the findings, “These results are not surprising to busy child neurologists/epileptologists. The well-recognized weight gain issue associated with valproate is clearly a ‘postpubertal’ phenomenon and rarely seen in younger children. In fact, weight loss can be seen in very young children on valproate. Children do respond differently than adults to medications and there can be large differences within childhood depending upon age. Postpubertal teens, however, are more likely to gain weight on valproate, similar to the adult experience. Certainly not all, or even most, gain weight, but the risk is there and must be closely monitored for. If a child really needs to be taking valproate and does begin to gain weight, our first action is to bring our clinic dietician on board to see if there are dietary and lifestyle changes that can be addressed. If the weight gain persists, then the drug needs to be changed if possible-this is one of the many ‘risk-benefit analyses’ that must be made when prescribing medication. We do pay close attention to a child’s nutritional status, body mass index (BMI) and weight trends over time and work closely with dieticians and our gastroenterology (GI) colleagues in addressing abnormalities.”

Wilfong further noted that, “Antiepileptic medications that are associated with weight gain, such as carbamazepine, gabapentin, pregabalin, and valproate, can be of benefit in some children with failure-to-thrive or other issues with low weight gain. On the other hand, antiepileptic drugs associated with weight loss, such as felbamate, topiramate, and zonisamide, can be of benefit for some children with obesity.”

Espinosa concluded, “Results from adults and adolescents [regarding side effects of antiepileptic drugs] cannot be routinely extrapolated to infants and children.”

References

1. Espinosa PS, Salazar JC, Yu L, Mendiondo MS, Robertson WC, Baumann RJ. Lack of valproic associated weight gain in prepubertal children. Neurology 2006;66(Suppl 2):A266.