Teratogenic and anticonvulsant effects of zinc and copper valproate complexes in zebrafish.

Valproic acid (VPA) is an antiepileptic drug (AED) that has the broadest spectrum across all types of seizures and epileptic syndromes. Unfortunately, approximately 30% of epileptic patients are refractory to the classical AED. Metal ions have been frequently incorporated into pharmaceuticals for therapeutic or diagnostic purposes and research. In this preliminary study, we assess the embryo toxicity and the anticonvulsant activity of 4 novel metallodrugs, with Zn+2 and Cu+2, a derivative of valproic acid and the N-donor ligand in an adult zebrafish epileptic seizure model induced by pentylenetetrazole. The most toxic complex was [Cu(Valp)2Bipy], in which the LC50 was 0.22 µM at 48 h post fertilization (HPF) and 0.12 µM at 96 HPF, followed by [Zn(Valp)2Bipy] (LC50 = 10 µM). These same metallodrugs ([Cu(Valp)2Bipy] 10 mM/kg and [Zn(Valp)2Bipy] 30 mM and 100 mM/kg) displayed superior activity, thus reducing the seizure intensity by approximately 20 times compared to sodium valproate (175 mM/kg). Overall, [Cu(Valp)2Bipy] showed the best anticonvulsant effects. However, because of the toxicity of copper, [Zn(Valp)2Bipy] is considered the most promising anticonvulsant for future studies.

Reversed phase liquid chromatography method with fluorescence detection of gemifloxacin in rat plasma and its application to the pharmacokinetic study.

A simple, accurate and precise high-performance liquid chromatographic method with fluorescence detection was developed and validated for the determination of gemifloxacin (GEM) in rat plasma using furosemide as internal standard (I.S.). Plasma samples were pretreated by direct deproteinization and all samples and standard solutions were chromatographed at 45°C using triethylamine solution (0.5%, v/v, pH 3.0±0.1), methanol and acetonitrile (63:30:7, v/v/v) as the mobile phase. Chromatographic resolution was achieved using a RP-C(18) column (Atlantis, Waters, 150 mm × 4.6 mm, 5 µm) at a flow rate of 1.0 mL min(-1) and an injection volume of 30 µL. The analytes were measured by fluorescence detection with excitation and emission wavelengths of 344 nm and 399 nm, respectively. The retention times for GEM and I.S. were approximately 7.5 and 12.6 min, respectively. The lower limit of quantitation (LLOQ) was 20 ng mL(-1) and the calibration curves were linear over a concentration range of 20-5000 ng mL(-1). The intra- and inter-day precisions, expressed by relative standard deviation (R.S.D.) were lower than 6.24% and 4.49%, respectively. The accuracy ranged from 91.3% to 112% and from 98.8% to 106% for the lower and upper limit of quantitation of the calibration curve, respectively. Ratio of peak area of analyte to I.S. was used for quantification of plasma samples. No interferences from endogenous substances were found. The recovery of GEM and I.S. from plasma was greater than 90%. Drug stability in plasma was shown at room temperature for 4h, after three freeze-thaw cycles for 24h, in freezer at -80°C for 60 days, and in the autosampler after processing for 12h. The utility of the assay was confirmed by the successful analysis of plasma samples from GEM pharmacokinetics studies in the rats after intravenous administration.