The dosage and frequency of lamotrigine administration for each patient must be prescribed carefully according to the disease, age, concomitant medications, and administration period. According to Pharmaceuticals and Medical Devices Agency (PMDA) reports, either the number of patients with adverse events caused by the inappropriate use of lamotrigine or the ratio of the patients who have benefited from the Relief System for Adverse Drug Reactions did not change even after the revision of the package insert in 2015. The procedure for auditing lamotrigine prescriptions was standardized to improve patient safety in our hospitals. The efficacy of standardization was evaluated by investigating the patients' records and prescriptions. A total of 77 patients treated with lamotrigine were examined to evaluate the appropriateness of the dosage and frequency of administration as well as the number of prescription enquiries made by pharmacists retrospectively. In addition, the presence of adverse events such as skin rash was examined using medical records. The number of inappropriate cases found and the prescription questions asked by pharmacists during the 24-month period before and after standardization were compared. The rate of inappropriate prescriptions after standardization was significantly lower than that before (12.1 vs. 29%; p<0.05). The rate of prescription questions raised after standardization was significantly higher than that before (37.0 vs. 1.7%; p<0.05). Moreover, there was no adverse event after standardization. Our standardization practice was effective to easily identify inappropriate prescriptions and provide physicians with the appropriate dosage or frequency of administration for the patients.
Keywords: adverse event; appropriate use; audit; lamotrigine; prescription question; skin rash.