Food-effect study of nilotinib in chronic myeloid leukaemia (NiFo study): Enabling dose reduction and relief of treatment burden.

OBJECTIVES: Taking advantage of its food-dependent bioavailability, the present study investigated the effect of a reduced dose taken with real-life meals on the pharmacokinetics (PK) of nilotinib in chronic myeloid leukaemia (CML) patients. METHODS: Nilotinib was taken fasted (300 mg BID, days 1-4) or with real-life meals (200 mg BID, days 5-11). Rich sampling (days 1, 3, 8, 11) allowed for non-compartmental PK analysis. Nilotinib exposure (AUC0-12 h  -Cmin -Cmax ) and its intra- and interpatient variability were compared between the two regimens. Adverse events were recorded by means of a patient diary and ECG monitoring. RESULTS: Fifteen patients aged 40-74 years participated. Nilotinib PK following 200 mg BID taken with a meal strongly resembled that of 300 mg BID taken fasted (Cmin percentile (P)10-P90: 665-1404 ng/mL and 557-1743 ng/mL, respectively). Meals delayed nilotinib absorption. Intra- and interpatient variability were not increased by intake with meals. Nilotinib with food was well tolerated. CONCLUSION: With support of therapeutic drug monitoring, the use of a reduced 200 mg nilotinib dose with real-life meals seems feasible and safe. Future (confirmatory) studies should further explore the usefulness of nilotinib dosing together with food, including the relationship with treatment efficacy as well as long-term effects on quality of life. CLINICAL TRIAL REGISTRATION: NTR5000 (Netherlands Trial Register, www.trialregister.nl).

An UPLC-MS detection method for the quantification of five antibiotics in human plasma.

BACKGROUND: An UPLC-MS detection method for the quantification of amikacin, flucloxacillin, meropenem, penicillin G and vancomycin was developed and validated. RESULTS: The calibration curves were found to be linear from 0.47 to 50 mg/l for amikacin, 1.28 to 135 mg/l for flucloxacillin, 0.75 to 80 mg/l for meropenem, 0.38 to 80 mg/l for penicillin G and 0.73 to 80 mg/l for vancomycin. Between- and within-run accuracy was ranged between 85 and 115%. Between and within imprecision expressed as CV was within 15%. CONCLUSION: The validated method was successfully applied to a PK study in very preterm and small for gestational age infants treated for nosocomial sepsis and/or meningitis.

Haematocrit corrected analysis of creatinine in dried blood spots through potassium measurement.

We developed a method for the analysis of creatinine in dried blood spot (DBS) samples to facilitate monitoring of renal function in combination with TDM of immunosuppressive drugs for transplant patients outside the hospital. An 8-mm disc of the DBS was punched, extracted and followed by LC-MS/MS analysis. The haematocrit proved to have a significant influence on the analysis of creatinine in DBS samples. As potassium is a suitable marker for haematocrit, we implemented a method for measuring potassium in DBS and correct the creatinine for haematocrit. For both creatinine and K(+) in DBS analytical and DBS, validation was performed, both components met the validation criteria and no other influences beside the haematocrit were detected. To assess the haematocrit correction, samples were compared to the 'golden' standard and plotted before and after correction. The correction showed a great improvement in agreement between the DBS assay and venous blood assay.

Rapid quantification of gabapentin, pregabalin, and vigabatrin in human serum by ultraperformance liquid chromatography with mass-spectrometric detection.

BACKGROUND: Gabapentin (GBP), pregabalin (PRG), and vigabatrin (VIG) are used for the prevention and treatment of epileptic seizures. The developed method was applied to samples from subjects participating in a pharmacokinetic study of GBP. METHODS: Sample pretreatment consisted of adding 20 µL of trichloroacetic acid (30%; vol/vol) and 200 µL of GBP-d4 in acetonitrile as an internal standard to 20 µL of serum. Chromatographic separation was performed on an Acquity separation module using a Kinetex RP18 column. The aqueous and organic mobile phases were 2 mM ammonium acetate supplemented with 0.1% formic acid in water and acetonitrile, respectively. The detection by a tandem quadrupole mass spectrometer, operating in the positive mode using multiple reaction monitoring, was completed within 2 minutes. RESULTS: The method was linear over the range of 0.03-25 mg/L for GBP, 0.03-25 mg/L for PRG, and 0.06-50 mg/L for VIG. The between- and within-run accuracies ranged from 90% to 107%. The between- and within-run imprecisions of the method were <10%. Stability data show no significant decrease of the analytes. A relative matrix effect of -1%, 0.2%, and -5% was determined for GBP, PRG, and VIG, respectively. CONCLUSIONS: A simple and sensitive ultraperformance liquid chromatography-tandem mass spectrometry method was developed and validated for the simultaneous quantification of GBP, PRG, and VIG in human serum. The reported method provided the necessary linearity, precision, and accuracy to allow the determination of GBP, PRG, and VIG for therapeutic drug monitoring and clinical research purposes.

Safety and efficacy of the immunosuppressive agent 6-tioguanine in murine model of acute and chronic colitis.

BACKGROUND: Oral thiopurines are effective and widely used in treatment of inflammatory bowel disease (IBD) in humans, although their use is limited due the development of adverse events. Here, we examine the efficacy and toxicity of oral treatment with 6-tioguanine (6-TG) and azathioprine (AZA) in a murine model of IBD. METHODS: We induced acute or chronic colitis in BALB/c mice by one or four cycles of 3% dextran sulphate sodium (DSS), respectively. Mice were treated by daily gavages of various dosages of 6-tioguanine, azathioprine, or by phosphate buffered saline (PBS) starting the first day of DSS or after two cycles of DSS, respectively. We monitored the efficacy and toxicity by measuring the weight change and serum alanine aminotransferase (ALT) activity and by disease severity and histology, at the end of the experiment. Moreover, we measured cytokine production after colon fragment cultivation by enzyme-linked immunoabsorbent assay and numbers of apoptotic cells in the spleen by flow cytometry. RESULTS: 6-TG is effective in the treatment of acute DSS-induced colitis in a dose-dependent manner and 40 µg of 6-TG is significantly more effective in the treatment of acute colitis than both AZA and PBS. This effect is accompanied by decrease of IL-6 and IFN-γ production in colon. We did not observe histological abnormalities in liver samples from control (PBS) or 6-TG treated mice. However, liver samples from most mice treated with AZA showed mild, yet distinct signs of hepatotoxicity. In chronic colitis, all thiopurine derivatives improved colitis, 20 µg of 6-TG per dose was superior. High doses of 6-TG led to significant weight loss at the end of the therapy, but none of the thiopurine derivatives increased levels of serum ALT. Both thiopurine derivatives reduced the proportion of apoptotic T helper cells, but a high production of both IL-6 and TGF-ß was observed only in colon of AZA-treated mice. CONCLUSIONS: Use of 6-TG in the treatment of experimental colitis in mice appears superior to AZA administration and placebo. In contrast to 6-TG, the use of AZA resulted in histological liver abnormalities.

Toxicokinetics of a dipyridamole (Persantin) intoxication: case report.

We report a case of a 51-year-old woman who was admitted to the hospital after ingestion of large doses of dipyridamole (12 g), temazepam (1 g) and oxazepam (0.2 g) with suicidal intent. The highest dipyridamole concentration that was measured in serum was 9.2 mg/L, which was paralleled by impaired platelet activation. For temazepam and oxazepam, peak serum concentrations were 8.5 and 1.3 mg/L, respectively. The patient was treated with activated charcoal, magnesium sulfate and aminophylline and could be discharged in good physical condition within 17 hours. This is the first report that provides toxicokinetic data and a corresponding pharmacodynamic effect after an intoxication with dipyridamole.

Validated liquid chromatography-tandem mass spectroscopy method for the simultaneous quantification of four antimycotic agents in human serum.

A liquid chromatography-tandem mass spectrometry method was developed and validated for the simultaneous quantification of voriconazole, fluconazole, posaconazole, itraconazole, and hydroxyitraconazole in human serum. A simple protein precipitation was used as sample pretreatment with ketoconazole as the internal standard. Chromatographic separation was performed on a Waters Alliance 2795 liquid chromatography system using a XBridge RP18 column. The mass spectrometer from Micromass was equipped with an electrospray ionization probe operating in the positive mode using multiple reaction monitoring. The method was linear over the range of 0.01 to 5.00 mg/L for itraconazole, 0.01 to 5.00 mg/L for OH-itraconazole, 0.02 to 10.00 mg/L for voriconazole, 0.06 to 30.00 mg/L for fluconazol, and 0.02 to 10.00 mg/L for posaconazole. The between- and within-run accuracy ranged from 92% to 110%. The between- and within-run imprecision of the method was less than 11%. The reported method provided the necessary linearity, precision, and accuracy to allow the determination of four antimycotic agents for therapeutic drug monitoring and pharmacokinetic-pharmacodynamic studies.

Quantitative analysis of sildenafil and desmethylsildenafil in human serum by liquid chromatography-mass spectrometry with minimal sample pretreatment.

A simple, sensitive and specific liquid chromatography tandem mass spectrometry method with minimal sample pretreatment was developed for the simultaneous analysis of sildenafil and its metabolite desmethylsildenafil in human serum. Sample pretreatment consisted of adding a methanolic solution of the internal standard vardenafil to the samples. After vortexing and centrifugation the samples were directly injected onto the C18 column using gradient elution. The aqueous and organic mobile phases were ammonium acetate 2 mM supplemented with 0.1% formic acid in water and methanol, respectively. The detection by a triple quadrupole mass spectrometer in positive ESI ionization mode was completed within 5 min. The lower limits of quantification for sildenafil and desmethylsildenafil are 1.0 ng/ml. The intra- and inter-day precisions measured as relative standard deviation were within 10% for both compounds over the linear range. Intra- and inter-day accuracy of sildenafil and desmethylsildenafil ranged from 92 to 103%. This method has been used in a clinical pharmacokinetic study of sildenafil in intensive care patients.