Comparative analysis of valproic acid concentrations in terms of dosing and clinical effect monitoring in different age patients with diagnosed epilepsy

• Main Authors: Agnieszka Cios (Author), Elżbieta Szczygieł-Pilut (Author), Sylwia Kozłowska (Author), Anna Zajączkowska-Dutkiewicz (Author), Łukasz Hońdo (Author), Anna Wesołowska (Author)
• Format: Book
• Published: Polish Pharmaceutical Society, 2022-05-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.
• Notes: 0014-8261; 10.32383/farmpol/150352
• Keywords: valproic acid; therapeutic drug monitoring; epilepsy; clinical patient condition; Pharmacy and materia medica; RS1-441
• Source: Farmacja Polska, Vol 78, Iss 3, Pp 111-122 (2022)

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 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 different age of epileptic patients. 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 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 group 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 patient's individual indications and clinical condition allows to achieve seizure-free period with good tolerance or optimal seizure control with minimal VPA side-effects.