The Comparison of HPLC and Turbidimetric Methods in the Measurement of Serum Antiepileptic Drug Concentrations

Aim: Many different methods have been used for detection of antiepielptic drug concentrations for many years in clinical chemistry laboratories. In our study we aimed to evaluate the performance of turbidimetry as a method for detection of serum antiepileptic drug concentrations by comparing it with HPLC technique. Material and Method: Measurements were performed in both methods teknion the blood samples of the epileptic patients who were in follow up in neurology and pediatrics clinics of Ministry of Health Ankara Education and Research Hospital. This study was carried on laboratory of biochemistry of the same hospital. 35 samples for carbamazepine, 31 for phenytoin and 30 for phenobarbital were taken into this study. Results: Within run CV values for HPLC technique in measurement of sera were as follows for each drug: Carbamazepine 1.57% and 3.62%; phenytoin 2.15% and 4.14%; and phenobarbital 1.53% and 4.34%. They were found in turbidimetric method as follows: Carbamazepine 2.66% and 7.03%; phenytoin 1.98% and 2.04% and phenobarbital 3.3%1 and 5.24%. There was a significant correlation between turbidimetric method and HPLC technique (for carbamazepine r= 0.95, phenytoin r= 0.97 and phenobarbital r= 0.86 ). The recovery rates for each drug in turbidimetry were satisfactory (carbamazepine R%= 80.4%, phenytoine 88% and phenobarbital 86.8%).They were as follows in HPLC technique: R%= 105%, 107%, 110%. Conclusion: HPLC technique is accepted as a reference method for detection of serum antiepileptic drug concentrations. The performance of turbidimetric method is weak when compared with HPLC technique. But because of the cost effectiveness and the short turn around time, turbidimetry was preferred in our country.