Ex vivo conversion of prodrug prothionamide to its metabolite prothionamide sulfoxide with different extraction techniques and their estimation in human plasma by LC-MS/MS

Push forward LC-MS-based therapeutic drug monitoring and pharmacometabolomics for anti-tuberculosis precision dosing and comprehensive clinical management

The spread of tuberculosis (TB), especially multidrug-resistant TB and extensively drug-resistant TB, has strongly motivated the research and development of new anti-TB drugs. New strategies to facilitate drug combinations, including pharmacokinetics-guided dose optimization and toxicology studies of first- and second-line anti-TB drugs have also been introduced and recommended. Liquid chromatography-mass spectrometry (LC-MS) has arguably become the gold standard in the analysis of both endo- and exo-genous compounds. This technique has been applied successfully not only for therapeutic drug monitoring (TDM) but also for pharmacometabolomics analysis. TDM improves the effectiveness of treatment, reduces adverse drug reactions, and the likelihood of drug resistance development in TB patients by determining dosage regimens that produce concentrations within the therapeutic target window. Based on TDM, the dose would be optimized individually to achieve favorable outcomes. Pharmacometabolomics is essential in generating and validating hypotheses regarding the metabolism of anti-TB drugs, aiding in the discovery of potential biomarkers for TB diagnostics, treatment monitoring, and outcome evaluation. This article highlighted the current progresses in TDM of anti-TB drugs based on LC-MS bioassay in the last two decades. Besides, we discussed the advantages and disadvantages of this technique in practical use. The pressing need for non-invasive sampling approaches and stability studies of anti-TB drugs was highlighted. Lastly, we provided perspectives on the prospects of combining LC-MS-based TDM and pharmacometabolomics with other advanced strategies (pharmacometrics, drug and vaccine developments, machine learning/artificial intelligence, among others) to encapsulate in an all-inclusive approach to improve treatment outcomes of TB patients.

Validation of a universal and highly sensitive two-dimensional liquid chromatography-tandem mass spectrometry methodology for the quantification of pyrazinamide, ethambutol, protionamide, and clofazimine in different biological matrices

A novel and potent anti-tuberculosis drug combination pyrazinamide (PZA), ethambutol (EMB), protionamide (PTO), and clofazimine (CFZ) that rapidly kills Mycobacterium tuberculosis (Mtb) in the lungs has been identified using the artificial-intelligence-enabled parabolic response surface approach. A universal and highly sensitive two-dimensional liquid chromatography-tandem mass spectrometry (2D-LC-MS/MS) method for the simultaneous determination of PZA, EMB, PTO, and CFZ in various biological samples in different states (liquid samples: plasma, bile, and urine; solid samples: tissue and feces) using simple pretreatment was established and validated. For the first dimension of this column-switching arrangement, the automated purification and enrichment of the drugs were achieved on a Polar-RP column. The subsequent analytical separation was performed on an Agilent Zorbax SB-Aq column, and the total loop time was 7.5 min. The positive-ionization mode with multiple reaction monitoring was used for detection. The sensitivity was good with no carry-over detected, and the lower limit of quantification ranged from 100 to 500 pg/mL. This quantification method was fully validated and proved to be robust in accordance with US Food and Drug Administration guidelines. High recoveries (85.3-111.4%) and accuracies (92.1-109.3%), together with high precision values (0.5-13.8%), were verified in all matrices. All standard curves showed favorable linearities with r2 > 0.995. This validated method was applied to study plasma pharmacokinetics, tissue distribution, and excretion in Sprague-Dawley rats after oral administration of the drug combination.

Impact of electrospray ion source platforms on matrix effect due to plasma phospholipids in the determination of rivastigmine by LC–MS/MS

Background: This study evaluates the performance of three electrospray ionization source designs to monitor the interference of plasma phospholipids for reliable estimation of rivastigmine by LC–MS/MS for method ruggedness. The variation in the area response due to matrix effects was assessed by post-column infusion, post-extraction spiking and standard-line slope methods. Results: The observed interference due to coeluting phospholipids (m/z: 524.0/184.0) at the retention time of rivastigmine was 39.5, 12.9 and 0.4% using angular spray, orthogonal spray and dual orthogonal ion source spray design, respectively. Similarly, %CV for standard line slopes was 6.9, 4.6 and 2.0, respectively. Conclusion: Z-spray source design provided better and efficient transfer of gas phase ions into the mass analyzer compared with angular and orthogonal spray. The study showed that Z-spray ion source provided minimum interference from phospholipids compared with other ion source designs.