Pharmacokinetics of diphenylboroxazolidones of L-α-amino acids with activity on the CNS: quantification in rat DBS by UPLC-MS/MS.

BACKGROUND: A growing number of boron-containing compounds exhibit many important biological activities; of particular interest are the α-amino acid borinic derivatives with activity in the CNS. A validated, sensitive and specific UPLC-MS/MS technique for quantification of the diphenylboroxazolidones of glycine (DBPX-gly), L-aspartate (DPBX-L-asp) and L-glutamate (DPBX-L-glu) in dried blood spots (DBSs) is presented. RESULTS: The most intense signal corresponds to compounds with (11)B. The extraction procedure was liquid elution of 3.2-mm punched DBSs with acetonitrile:aqueous formic acid 0.1% (80:20 v/v). Assays proved to be linear, falling accurately and precisely within the range of 0.3-50 µg/ml for DPBX-L-asp and DPBX-L-glu and 0.1-5 µg/ml for DBPX-gly. Chromatograms exhibit clean 2.0-min running time peaks and S/N ratios for the LLOQ were approximately 15:1. The technique was used to evaluate the pharmacokinetics of the molecules and to correlate these with timecourse toxic effects. CONCLUSION: DBSs represent an advantage for the collection of small volumes of samples, and also in terms of processing and storage. UPLC-MS/MS allow us not only to identify the isotopic pattern of boron in DBPX, but also to quantify them with accuracy and specificity. Pharmacokinetics of these molecules exhibit a high apparent volume of distribution; it suggests a preference of DPBX-amino acids for fatty tissues such as the CNS.

Therapeutic effect of a novel oxazolidinone, DA-7867, in BALB/c mice infected with Nocardia brasiliensis.

BACKGROUND: Mycetoma is a chronic infectious disease of tropical and subtropical countries. It is produced by true fungi and actinobacteria. In México, Nocardia brasiliensis is the main causative agent of mycetoma, producing about 86% of the cases; the gold standard for the therapy of mycetoma by N. brasiliensis is the use of sulfonamides which give a 70% cure rate. The addition of amikacin to this regime increases to 95% the cure rate; however, the patients have to be monitored for creatinine clearance and audiometry studies because of the potential development of side effects. Because of that it is important to search for new active compounds. In the present work, we evaluated the in vivo effect of DA-7867, an experimental oxazolidinone, on the development of experimental mycetomas by N. brasiliensis in BALB/c mice. METHODOLOGY/PRINCIPAL FINDINGS: In order to determine the optimal dose utilized to apply to the animals, we first determined by HPLC the plasma levels using several concentrations of the compounds. Based on these results, we used 10 and 25 mg/kg subcutaneously every 24 hr; DA-7867 was also supplied in the drinking water at a calculated dose of 25 mg/kg. As a control we utilized linezolid at 25 mg/kg, a compound active in murine and human infections, three times a day. The mice were infected in the right footpad with a young culture of N. brasiliensis HUJEG-1, and one week later we started the application of the antimicrobials for six more weeks. After that we compared the development of lesions in the groups injected with saline solution or with the antimicrobials; the results were analyzed by the variance ANOVA test. DA-7867 was able to reduce the production of lesions at 25 mg/kg, when given either subcutaneously or in the drinking water. CONCLUSIONS/SIGNIFICANCE: The experimental oxazolidinone DA-7867 is active in vivo against N. brasiliensis, which opens the possibility of using this drug once it is accepted for human application. Since oxazolidinones seem to be active against a wide spectrum of actinobacteria, it is possible they could be used in human cases of mycetoma by other actinomycetales, such as Streptomyces somaliensis, highly prevalent in Sudan, or Actinomadura madurae and A. pelletieri, which are commonly observed in Africa and India.

Simultaneous determination and validation of antimicrobials in plasma and tissue of actinomycetoma by high-performance liquid chromatography with diode array and fluorescence detection.

A simple, precise, and reliable chromatographic method was developed for the simultaneous determination in plasma and infected tissue of five antimicrobials proposed for the treatment of actinomycotic mycetoma: amoxicillin, trimethoprim, linezolid, sulfamethoxazole and garenoxacin. Separation of the analytes was achieved on an Atlantis dC18 column (150 mm x 4.6 mm, ID 5 microm) with a mobile phase composed of acetonitrile and trifluoroacetic acid (ATF) 0.1% (v/v) using a gradient program. The detection was carried out using a diode array detector at 254 nm and in a fluorescence detector at wavelengths of excitation and emission of 292 nm and 392 nm for linezolid and sulfamethoxazole, and 292 nm and 408 nm for garenoxacin, respectively. The intraday precision was in the range of 0.7-15% of relative standard deviations (%R.S.D.) for plasma and 1-18% for tissue. Linearity range was from 2.4 to 20 microg/ml for amoxicillin, 0.3 to 20 microg/ml for trimethoprim, sulfamethoxazole and linezolid, and 0.3 to 10 microg/ml for garenoxacin. Acetonitrile was used to precipitate proteins from plasma. Recoveries in plasma ranged from 71% to 118% and in infected tissue from 78% to 122%. Limits of detection (LODs) were 1.2 and 0.5 microg/ml for amoxicillin in plasma and tissue, respectively and 0.15 and 1.2 microg/ml in plasma and tissue, respectively for the other antimicrobials. The method can be applied for individual or simultaneous determination of the antimicrobials in plasma and tissue of mouse infected with actinomycetoma.