Nimorazole

A rapid and sensitive determination of hypoxic radiosensitizer agent nimorazole in rat plasma by LC-MS/MS and its application to a pharmacokinetic study.[Pubmed:25845449]

Biomed Chromatogr. 2015 Oct;29(10):1575-80.

A highly sensitive, accurate and robust LC-MS/MS method was developed and validated for determination of Nimorazole (NMZ) in rat plasma using metronidazole (MNZ) as internal standard (IS). The analyte and IS were extracted from plasma by precipitating protein with acetonitrile and were chromatographed using an Agilent Poroshell 120, EC-C18 column. The mobile phase was composed of a mixture of acetonitrile and 0.1 % formic acid (85:15 v/v). The total run time was 1.5 min and injection volume was 5 muL. Multiple reaction monitoring mode using the transitions of m/z 227.1 --> m/z 114.0 for MNZ and m/z 172.10 --> m/z 128.1 for IS were monitored on a triple quadrupole mass spectrometer, operating in positive ion mode. The calibration curve was linear in the range of 0.25-200 ng/mL (r(2) > 0.9996) and the lower limit of quantification was 0.25 ng/mL in the rat plasma samples. Recoveries of NMZ ranged between 88.05 and 95.25%. The precision (intra-day and inter-day) and accuracy of the quality control samples were 1.25-8.20% and -2.50-3.10, respectively. The analyte and IS were found to be stable during all sample storage and analysis procedures. The LC-MS/MS method described here was validated and successfully applied to pharmacokinetic study in rats.

IAEA-HypoX. A randomized multicenter study of the hypoxic radiosensitizer nimorazole concomitant with accelerated radiotherapy in head and neck squamous cell carcinoma.[Pubmed:25913070]

Radiother Oncol. 2015 Jul;116(1):15-20.

PURPOSE: To test the hypothesis that radiotherapy (RT) of head and neck squamous cell carcinoma (HNSCC) can be improved by hypoxic modification using Nimorazole (NIM) in association with accelerated fractionation. MATERIALS AND METHODS: The protocol was activated in March 2012 as an international multicenter randomized trial in patients with HNSCC. Tumors were treated to a dose of 66-70Gy, 33-35 fractions, 6 fractions per week. NIM was administered in a dose of 1.2gperm(2), 90min before the first daily RT fraction. The primary endpoint was loco-regional failure. The trial was closed prematurely by June 2014 due to poor recruitment. An associated quality assurance program was performed to ensure the consistency of RT with the protocol guidelines. RESULTS: The trial was dimensioned to include 600 patients in 3years, but only 104 patients were randomized between March 2012 and May 2014 due to the inability to involve three major centers and the insufficient recruitment rate from the other participating centers. Twenty patients from two centers had to be excluded from the analysis due to the unavailability of the follow-up data. Among the remaining 84 patients, 82 patients were evaluable (39 and 43 patients in the RT+NIM and the RT-alone arms, respectively). The treatment compliance was good with only six patients not completing the full planned RT course, and 31 patients (79%) out of 39 allocated for NIM, achieving at least 90% of the prescribed drug dose. At the time of evaluation, 40 patients had failed to achieve persistent loco-regional tumor control, and a total of 45 patients had died. The use of NIM improved the loco-regional tumor control with an 18month post-randomization cumulative failure rate of 33% versus 51% in the control arm, yielding a risk difference of 18% (CI -3% to 39%; P=0.10). The corresponding values for overall death was 43% versus 62%, yielding a risk difference of 19% (CI -3% to 42%; P=0.10). Sixteen patients, out of 55 patients analyzed for hypoxic gene expression, were classified as having more hypoxic tumors. Such patients, if treated with RT alone, had a higher loco-regional tumor failure rate as compared to the rest of the patients with known hypoxic status (P=0.05). CONCLUSION: Although the trial was incomplete and suffered from a small number of patients, the results suggested an improvement in loco-regional tumor control and overall survival in patients with advanced HNSCC given the hypoxic modifier NIM in addition to accelerated fractionation RT. However, the trial also revealed that conducting multicenter and multinational study combining drug and RT in developing countries may suffer from uncontrolled and unsolvable problems.

Photoelectron Spectra and Electronic Structures of the Radiosensitizer Nimorazole and Related Compounds.[Pubmed:26344652]

J Phys Chem A. 2015 Oct 1;119(39):9986-95.

Soft X-ray photoelectron spectroscopy has been used to investigate the radiosensitizer Nimorazole and related model compounds. We report the valence and C, N, and O 1s photoemission spectra and K-edge NEXAFS spectra of gas-phase Nimorazole, 1-methyl-5-nitroimidazole, and 4(5)-nitroimidazole in combination with theoretical calculations. The valence band and core level spectra are in agreement with theory. We determine the equilibrium populations of the two tautomers in 4(5)-nitroimidazole and find a ratio of 1:0.7 at 390 K. The NEXAFS spectra of the studied nitroimidazoles show excellent agreement with spectra of compounds available in the literature that exhibit a similar chemical environment. By comparing 1-methyl-5-nitroimidazole (single tautomer) with 4(5)-nitroimidazole, we are able to disentangle the photoemission and photoabsorption spectra and identify features due to each single tautomer.