Heterozygous mutations in the GBA1 gene, encoding the enzyme glucocerebrosidase (GCase), are major risk factors for Parkinson’s Disease (PD). Ambroxol, a small chaperone originally used as a mucolytic agent, has been shown to cross the blood–brain barrier, enhance GCase activity, and reduce α-synuclein levels, making it a promising therapeutic candidate for disease-modifying effects in GBA1-associated PD (GBA1-PD). This study aimed to develop a method to quantify ambroxol levels in human plasma and cerebrospinal fluid (CSF) using liquid chromatography–tandem mass spectrometry (LC-MS/MS). Ambroxol was determined by online solid-phase extraction (SPE), coupled with LC-MS/MS, by gradient elution on a monolithic column. Detection employed a 3200 QTRAP tandem mass spectrometer in the positive electrospray ionization mode. Calibration curves exhibited linearity across the analyzed ranges in both plasma and CSF. The recovery rate ranged from 106.7% to 113.5% in plasma and from 99.0% to 103.0% in CSF. No significant matrix effect was observed. Intra-day and inter-day precisions were below 11.8% in both matrices, and accuracy ranged from 89.9% to 103.1% in plasma and from 96.3% to 107.8% in CSF. We evaluated and confirmed the stability of the analyte in plasma and CSF across various storage conditions. The method was successfully validated according to European Medicine Agency (EMA) guidelines and its applicability was confirmed in the context of a multicenter, randomized, double-blind, placebo-controlled, phase II study, designed to monitor the ambroxol levels in the plasma and CSF of GBA1-PD.

Perampanel (PER) is a third‐generation antiseizure medication (ASM) with a well‐established concentration–effect relationship. Saliva represents a non‐invasive alternative to plasma for therapeutic drug monitoring (TDM) of PER, as it reflects the free plasma fraction. Volumetric absorptive microsampling (VAMS) enables standardized, patient‐friendly saliva collection. This study aimed to clinically validate saliva‐VAMS by directly comparing it with conventional liquid saliva sampling for PER quantification. In a prospective study, saliva was collected from 11 people with epilepsy receiving PER therapy (dose range = 2–10 mg/day) using both VAMS and conventional saliva sampling. PER concentrations were measured by liquid chromatography coupled with tandem mass spectrometry and compared using repeated measures Bland–Altman analysis and Lin's concordance correlation coefficient to evaluate agreement between methods. PER concentrations measured in saliva‐VAMS showed excellent agreement with those obtained from conventional saliva sampling, with mean bias of −0.126 ng/mL (95% confidence interval = −0.582 to 0.330). No relevant constant or proportional bias was observed, and limits of agreement were within predefined acceptance criteria. Concordance between methods was high, supporting analytical equivalence. The demonstrated interchangeability between saliva‐VAMS and conventional saliva sampling supports adoption of saliva‐VAMS in clinical TDM workflows, enabling standardized fixed‐volume collection, simplified storage/transport, and potential home‐based sampling for remote dose optimization of PER and potentially other ASMs.

This study describes the development and validation of a fully automated workflow for serum sample preparation, enabling the quantitative determination of cannabidiol (CBD) and its active metabolite, 7-hydroxy-CBD, via liquid chromatography coupled with tandem mass spectrometry (LC–MS/MS) analysis. Implemented on an automated platform, the workflow performs key steps such as solvent dispensing, mixing, centrifugation, filtration, and supernatant transfer, producing 96-well plates ready for analysis. Human serum samples were obtained from patients with epilepsy treated with CBD. All samples were processed using both manual and automated methods to evaluate method agreement. Quantification was performed by LC–MS/MS with CBD-d₃ as the internal standard (IS). Method validation was conducted in accordance with European Medicine Agency (EMA) guidelines, confirming that the automated protocol meets the recommended acceptance criteria for both intraday and interday precision and accuracy. Calibration curves demonstrated excellent linearity across the concentration ranges. Comparative analysis using Passing–Bablok regression and Bland–Altman plots demonstrated strong agreement between the methods. These findings support the clinical applicability of the automated method for the therapeutic drug monitoring (TDM) of CBD and 7-hydroxy-CBD, and its robust performance and scalability provide a solid foundation for the development of an expanded analytical panel covering a broader range of antiseizure medications (ASMs), enabling more standardized TDM protocols in clinical practice.