Relationship between Topiramate concentrations in serum and saliva of Thai Epileptic patients

Abstract

The objective of this study was to determine the correlation between serum and saliva topiramate concentrations in Thai epileptic patients. The correlation equation was verified using saliva and serum topiramate concentrations of unrelated patients. The study was conducted at the Out-patient Epilepsy Clinic, Department of Medicine Neurology Unit, Pramongkutklao Hospital. Patient aged between 15-60 years and receiving topiramate were included into this study. The correlation equation between serum and saliva topiramate concentrations were constructed from 10 patients, receiving topiramate monotherapy. The blood and saliva samples were collected at the time before the morning dose and at 1, 2, 4, 6 and 8 hours after topiramate ingestion. Also, blood and saliva samples of 30 patients were collected at the time before the morning dose and at 2 hours after topiramate ingestion using to verified the correlation equation. Blood and saliva samples were measured by turbidimetric immunoassay technique. Serum and saliva topiramate concentrations were linearly correlated with a correlation coefficient of 0.919 (p < 0.001), and the regression equation of this relationship was y = 0.962x + 1.197 (using all the data analyzed from samples collected at the time before and at 1, 2, 4, 6 and 8 hours after topiramate ingestion). Using the correlation equation, saliva topiramate concentrations of 30 patients were used to calculated serum topiramate concentrations. The result showed that there was no significant difference between calculated topiramate concentration and apparent topiramate concentration in serum. The results of this study support the use of saliva as an alternative to serum for monitoring topiramate therapy.