Introduction: Product switching followed by suspected adverse events are common and unsettling for antiepileptic drugs. The objective of this case study was to describe the investigation performed after report of suspected therapeutic failure in pediatric patients following a switch to a different valproate manufacturer and identify strategies concerning medication management for improving therapeutic outcomes. Case description: It was reported that different pediatric patients' condition changed (agitation/ seizures) after refilling the same drug prescription (sodium valproate syrup) from a different manufacturer. Medical staff reported a suspected therapeutic failure and some units of the product batch associated with the problem were seized by the local Post-marketing Surveillance Service for investigation of potential quality deviations. The seized units were evaluated by the State's Surveillance Laboratory, nevertheless, drug potency was found to be 98.7%. Conclusion: We consider that the reported event could be associated with aspects of medication use, i.e. potential dose measurement deviations resulting from remaining of residual liquid in the cup or eventual delay at prescription refilling process and consequential - even though brief - pharmacotherapy discontinuity. Patient education and counseling by pharmacists are essential for preventing drug-related problems and enhancing positive outcomes of pharmacotherapy.