A 5-Year Study of Lithium and Valproic Acid Drug Monitoring in Patients with Bipolar Disorders in an Italian Clinical Center

Therapeutic drug monitoring (TDM) is an effective tool used to improve the pharmaco-logical treatment in clinical practice, especially to detect subtherapeutic drug plasma concentration(Cp) in order to consider a change of dosage during treatment and reach its putative therapeuticrange. In this study, we report the Cp values of lithium and valproic acid (VPA), alone and incombination, mostly in bipolar patients admitted to an Italian clinical center of the University ofPisa during the years 2016–2020, which include 12,294 samples of VPA, 7449 of lithium and 1118of both in combination. Lithium and VPA are the most utilized drugs in treating bipolar disorders,and their TDM is strongly recommended by recent guidelines. In relation to lithium Cp monitoring,several studies have underlined that 0.5–0.8 mmol/L is the optimal range for chronic treatment, andbelow 0.4 mmol/L, it is unlikely to produce a clinical response. For VPA, the therapeutic range is50–100 μg/mL and a linear correlation between Cp and clinical efficacy has been proposed, wherebelow 50 μg/mL, the clinical efficacy of VPA has not been proven thus far. Toxic levels of bothdrugs were rarely found in our study, while a high percentage of patients, about one-third, hadsub-therapeutic Cp during their treatments. In addition, in several cases of patients receiving multipleblood sampling, the initial subtherapeutic Cp changed only partially without reaching its therapeuticwindow. In relation to age, we found a higher percentage of lithium and VPA Cp values in range inthe adolescents than in the adults and elderly groups. No differences were reported when analyzingthe distribution of Cp values in males and females. In conclusion, this present study suggests thatTDM is widely used by many specialists, but there is still a window of improvement for optimizingpharmacological treatments in clinical practice. (14) (PDF) A 5-Year Study of Lithium and Valproic Acid Drug Monitoring in Patients with Bipolar Disorders in an Italian Clinical Center. Available from: https://www.researchgate.net/publication/357902306_A_5-Year_Study_of_Lithium_and_Valproic_Acid_Drug_Monitoring_in_Patients_with_Bipolar_Disorders_in_an_Italian_Clinical_Center [accessed Jan 24 2022].