Quantification of NVP Plasma Levels

The NVP plasma concentrations were quantified using a tandem quadrupole mass spectrometer (LC/MS/MS) designed for ultra-high performance: Xevo TQ-S (Waters Corporation, Massachusetts) as described by Reddy et al^{[17 ]} modified in our previous publication.^{[15 (link),16 (link)]} Plasma samples were extracted using Bond Elut C18 cartridges, according to the manufacturer’s instructions (Agilent Technologies, California). The eluents were completely evaporated using Thermo Scientific Reacti-Vap evaporators (Thermo Fisher Scientific Inc., California) at 37°C for 30 minutes. This was then reconstituted using 100 µL of equal parts 1:1 acetonitrile and water, vortexed briefly, transferred into 50 mL capped vials, and placed into Xevo TQ-S (Waters Corporation) for quantification. Approximately 1 µL of the sample was injected automatically into the LC/MS/MS instrument and quantified within 5 minutes. NVP plasma concentrations were categorized as <3400 ng/mL (below the therapeutic range), 3400 to 6000 ng/mL (therapeutic range), or >6000 ng/mL (above the therapeutic range).^{[18 (link),19 (link)]}