AIMTo establish an HPLC-fluorescent spectrometric method for the determination of mexiletine hydrochloride in plasma after derivatization with fluram.

METHODSFluram acetone solution was added to the deproteinized plasma with acetone to obtain the derivative of mexiletine. The HPLC method was performed on a column of Allitima C18 (150 mm x 4.6 mm, 5 microns) with the mobile phase of methanol-water-diethylamine-phosphoric acid buffer (2.4 mol.L-1, pH 4.0) (70:28:2), and the detective wavelength were set at Ex 392 nm and Em 480 nm.

RESULTSMexiletine has a liner range over the concentration range from 0.100-6.400 mg.L-1. The lowest detectable concentration of this method was 5 micrograms.L-1 (S/N > or = 4). The intra-day and inter-day RSDs were 1.34%-5.31%, respectively.

CONCLUSIONThis method is simple, selective and can be used for therapeutic drug monitoring (TDM) and pharmacokinetic studies of mexiletine.

Anti-Arrhythmia Agents ; blood ; pharmacokinetics ; Chromatography, High Pressure Liquid ; methods ; Fluorescamine ; chemistry ; Humans ; Mexiletine ; blood ; pharmacokinetics

OBJECTIVETo identify a new peptide deformylase (PDF) gene (Genebank Accession AY238515) from Enterococcus faecium and to establish a new screening model targeted on PDF.

METHODSA new PDF gene was identified by BLAST analysis and PCR and was subsequently over-expressed in the prokaryotic expression host E. coli B121(DE3). Over-expressed protein was purified for enzymatic assay by metal affinity chromatography and a new screening model was established for novel antibiotics.

RESULTA new PDF gene of Enterococcus faecium was identified successfully. Ten positive samples were picked up from 8000 compound library and the microbial fermentation broth samples.

CONCLUSIONA new PDF of gene Enterococcus faecium was first identified and the model had a high efficacy. Positive samples screened may be antibacterial agents of broad spectrum.

Amidohydrolases ; antagonists & inhibitors ; genetics ; isolation & purification ; Amino Acid Sequence ; Anti-Bacterial Agents ; therapeutic use ; Cloning, Molecular ; Drug Evaluation, Preclinical ; Enterococcus faecium ; enzymology ; genetics ; Fluorescamine ; Fluorescence ; Hydrogen-Ion Concentration ; Indicators and Reagents ; Kinetics ; Models, Molecular ; Molecular Sequence Data ; Temperature