Agnieszka Cios, Elżbieta Szczygieł-Pilut, Sylwia Kozłowska, Anna Zajączkowska-Dutkiewicz, Łukas
Comparative analysis of valproic acid concentrations in terms of dosing and clinical effect monitoring in different age patients with diagnosed epilepsy
2022-05-30
Subject of research. Therapy drug monitoring under the control of valproic acid (VPA) is now a well-established tool for the treatment of epilepsy. The pharmacokinetic variability of VPA and inter-individual differences in epilepsy type/seizure severity depending on patients’ age determine the serum concentration of this drug in an individual patient. The application of the “individual therapeutic concentration” may be a useful indicator taking into account the clinical condition of a patient.
Aim. The aim was to compare values of stationary VPA concentrations in terms of dosing and clinical effect monitoring in epileptic patients of different ages.
Methods. Thirty-three patients at age 20–70 years were divided into three groups: I – 20–25 years (n = 15), II – 26–39 years (n = 9), III – 40–70 years (n = 9). Nine patients were treated with VPA in monotherapy, others received VPA with at least one antiepileptic drug (n = 24). Plasma VPA Cssmin values were measured, at steady state, using the commercial CEDIA® Valproic Acid II Assay.
Results. VPA Cssmin values in groups I, II, and III were within the therapeutic range: 93, 56, and 30%; above it: 0, 33, and 55%, and below it: 6, 22, and 0%, respectively. The percentage of patients with the least frequent seizure was highest in group I (60%) compared to II (54%) and III (44%). The highest frequency of seizures was in group III (25 seizures/week) compared to group I (6.5 seizures/week). The percentage of patients with 1 attack in 1–7 days was comparable in groups: I (13%), II (12%), and III (12%). On the other hand, the percentage of patients free from epileptic seizures (> 1 year) was the highest in group I (53%) compared to groups II (44%) and III (22%).
Conclusions. The reasons for the obtained differences could be drug interactions, nutritional style, and the lack of compliance. The unpredictable VPA dose-concentration-clinical effect supports the need to optimize the therapy and define “individual therapeutic concentration”. Using it in practice along with the patient’s individual indications and clinical condition allows for achieving a seizure-free period with good tolerance or optimal seizure control with minimal VPA side effects.
Keywords: valproic acid, therapeutic drug monitoring, epilepsy, clinical patient condition.
© Farm Pol, 2022, 78 (3): 111–122