Sensitive, specific, and dynamic LC-MS/MS assays have been developed and validated for the multiplexed quantification TAF and TFV, as well as an independent assay for CMX157 quantification, in plasma. The described methods meet sufficient throughput criteria to support large research trials.
The L-type calcium channel gene, CACNA1C, is a validated risk gene for schizophrenia and the target of calcium channel blockers. Carriers of the risk-associated genotype (rs1006737 A allele) have increased frontal cortical activity during working memory and higher CACNA1C mRNA expression in the prefrontal cortex. The aim of this study was to determine how the brain-penetrant calcium channel blocker, nimodipine, changes brain activity during working memory and other cognitive and emotional processes. We conducted a double-blind randomized cross-over pharmacoMRI study of a single 60 mg dose of oral nimodipine solution and matching placebo in healthy men, prospectively genotyped for rs1006737. With performance unchanged, nimodipine significantly decreased frontal cortical activity by 39.1% and parietal cortical activity by 42.8% during the N-back task (2-back > 0-back contrast; PFWE < 0.05; n = 28). Higher peripheral nimodipine concentrations were correlated with a greater decrease in activation in the frontal cortex. Carriers of the risk-associated allele, A (n = 14), had a greater decrease in frontal cortical activation during working memory compared to non-risk allele carriers. No differences in brain activation were found between nimodipine and placebo for other tasks. Future studies should be conducted to test if the decreased cortical brain activity after nimodipine is associated with improved working memory performance in patients with schizophrenia, particularly those who carry the risk-associated genotype. Furthermore, changes in cortical activity during working memory may be a useful biomarker in future trials of L-type calcium channel blockers.
Background: Medroxyprogesterone acetate (MPA) is a common contraceptive agent taken both orally and as a subcutaneous or intramuscular injection. Current LC-MS/MS methods for MPA quantification require large sample volumes and low-throughput analytical run times. Therefore, there are opportunities to improve upon existing methods for MPA quantification. Methods: MPA was extracted from 600 μL plasma, evaporated to dryness, and the reconstituted solution was injected onto a Waters Acquity liquid chromatography (LC) system via an Agilent Zorbax Eclipse-Plus C18 2.1 × 50 mm (5.0 μm) column. MPA and its internal standard were monitored on a QTRAP ® 5500 mass analyzer operated in positive ionization mode. The method was validated according to the Food and Drug Administration Bioanalytical Method Validation guidelines.
Results:The analytical measuring range of the assay was 200 -10 000 pg/mL. QC samples prepared at the lower limit of quantification (LLOQ; 200 pg/mL) and low (600 pg/mL), mid (1750 pg/mL), and high (8500 pg/mL) levels showed interassay precision and accuracy ≤15.2% and ≤±9.6%, respectively. Stability-challenged samples yielded ≤15% from freshly prepared samples. Dilutional and matrix effects studies were also acceptable. The assay was also assessed in participants prescribed depot medroxyprogesterone acetate; observed concentrations were within the dynamic range of the assay. Conclusions: An LC-MS/MS method for the quantification of MPA in plasma has been developed and validated. The described method is sufficiently sensitive and robust to quantify MPA in plasma and meets the criteria to support clinical trials.
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