Monitoring of anti-tuberculosis drug concentrations and dose adjustment can be helpful in cases that show poor response to treatment. Here, we describe a method that can rapidly and simultaneously measure the blood concentrations of four anti-tuberculosis drugs (isoniazid, rifampicin, pyrazinamide, and ethambutol) and two major metabolic ratios (acetylisoniazid/isoniazid and 25-desacetylrifampicin/rifampicin) using high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS). A C18 reversed-phase column and gradients of methanol in 0.3% formic acid and water were used for HPLC separation. The drug concentrations were determined by multiple reaction monitoring in positive ion mode and the assay performance was evaluated. We determined peak concentration ranges for each drug and acetylisoniazid/isoniazid and 25-desacetylrifampicin/rifampicin ratios by analyzing 2-h post-dose samples in patients treated with standard dosing as a first-line treatment. The preparation of 20 samples including two steps of deproteinization with 50% and 100% methanol was performed within 20 min and chromatographic separation was achieved within 4 min/sample. Interassay calibration variability data obtained over concentrations of 0-8 microg/mL for isoniazid and ethambutol and 0-80 microg/mL for rifampicin and pyrazinamide showed a linear and reproducible curve. Within-run and between-run imprecision (CVs) were 1.9-5.5% and 3.5-10.5% and the lower limits of detection and quantification were 0.01-0.5 microg/mL and 0.05-1.0 microg/mL, respectively. The isoniazid concentration was found to be inversely correlated to the acetylisoniazid/isoniazid ratio (R=-0.739, P<0.001). The devised method allows for the simple, rapid, sensitive and reproducible quantification of isoniazid, rifampicin, pyrazinamide, ethambutol and their two metabolic ratios and should be helpful for therapeutic drug monitoring in tuberculosis patients.

Five N-methyl-N-R-N,N-bis(2-hydroxyethyl) ammonium bromides (R = -benzyl (chloride, BNQAS), -dodecyl (C12QAS), -tetradecyl (C14QAS), -hexadecyl (C16QAS), -octadecyl (C18QAS)) were prepared based on N-methyldiethanolamine (MDEA) and halohydrocarbon. Five QAS were characterized by FTIR, NMR, and MS. BNQAS, C12QAS, C14QAS, and C16QAS were confirmed by X-ray single-crystal diffraction. Their antibacterial properties indicated good antibacterial abilities against E. coli, S. aureus, B. subtilis, especially C12QAS with the best antibacterial ability (100% to E. coli, 95.65% to S. aureus, and 91.41% to B. subtilis). In addition, C12QAS also displayed the best antifungal activities than BNQAS and C18QAS against Cytospora mandshurica, Botryosphaeria ribis, Physalospora piricola, and Glomerella cingulata with the ratio of full marks. The strategy provides a facile way to design and develop new types of antibacterial drugs for application in preventing the fruit rot, especially apple.

Objectives: Therapeutic drug monitoring (TDM) of anti-tuberculosis (TB) drugs is beneficial for patients responding slowly to treatment and those with multidrug-resistant TB. We used ultra-performance liquid chromatographytandem mass spectrometry (UPLC-MS/MS) to develop a rapid method for simultaneously measuring the blood concentrations of nine second-line anti-TB drugs: streptomycin, kanamycin, clarithromycin, cycloserine, moxifloxacin, levofloxacin, para-aminosalicylic acid, prothionamide and linezolid.Methods: Serum samples were extracted with acidified methanol and neutralized with NaOH. A Waters Acquity HSS T3 column and gradients of ammonium formate and acetonitrile in 0.1% formic acid were used for UPLC separation. Drug concentrations were determined by multiple reaction monitoring in positive ion mode, and assay performance was evaluated. We applied this method to TDM, analysing random serum samples from 85 patients treated with second-line drugs.Results: Sample preparation using acidified methanol extraction followed by neutralization yielded good recovery and ionization efficiency, with chromatographic separation achieved within 3 min per sample. Within-run and between-run precisions were 1.7% -7.5% and 1.7% -12.4%, respectively, at concentrations representing low and high levels for the nine drugs. Lower limits of detection and quantification were 0.025-0.5 and 0.25 -5.0 mg/mL, respectively. Linearity was acceptable at five concentrations for each drug. No ion suppression was observed at the retention time for most compounds, except for streptomycin, kanamycin and cycloserine, which were eluted close to the void volume of the column. In a limited pilot study, all quantifiable human samples had values within the validated assay ranges. Conclusions:The performance of our MS/MS detection technique was generally acceptable. The method provided rapid, sensitive and reproducible quantification of nine second-line anti-TB drugs and should facilitate drug monitoring during treatment.

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