Validation of a chromatographic method to determine E-6006 and its metabolite E-6332 in rat and dog plasma by solid-phase extraction and capillary gas chromatography. Application in pharmacokinetics.
E-6006, 5-(alpha-[2-(dimethylamino)ethoxy]-2-thienylmethyl)-1-methyl-1H-pyrazole is a new antidepressive compound and E-6332, 5-(alpha-[2-(methylamino)ethoxy]-2-thienylmethyl)-1-methyl-1H-pyrazole is its desmethylate metabolite. With the aim of quantifying E-6006 and E-6332, simultaneously in rat or dog plasma, a method of analysis based on solid-phase extraction coupled with capillary gas chromatographic system with N-P detection was developed and validated. E-6006, E-6332 and its internal standard (E-4018) were isolated from plasma using an off-line semiautomatic solid-phase extraction method. Gas chromatography separations were carried out by means of 12 m length, 0 2 mm (i.d.) and 0.33 microm (f.t.) ULTRA 1 type capillary column in splitless mode of injection at 190 degrees C, with a TSD or specific nitrogen--phosphorus detector. No peaks interfering with the quantification of E-6332 and E-6006 were observed. The limit of quantification was 5 ng/ml with a precision and accuracy <17%. The peak height ratios were proportional to E-6332 and E-6006 concentration over the range from 5 to 600 ng/ml (r(2)>0.998). Mean recoveries of E-6332, E-6006 and internal standard from rat plasma were between 57.1 and 82.6. Intra-assay precision coefficients were <8.0 and <11.8%, respectively, for E-6332 and E-6006, with an accuracy <12.6 and <9.7%. Both inter-assay precision and accuracy were within acceptable limits (<15%). In dog, the results were very similar to those obtained in rat. To show an example of the suitability of the method to determine E-6332 and E-6006, plasma profiles obtained after single oral and intravenous administration of 20 mg/kg to rats and 25 mg/kg to dogs are reported.
Puig
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S
Department of Pharmacokinetics and Metabolism, Laboratorios Dr. Esteve, S.A. Av. Mare de Déu de Montserrat 221, 08041 Barcelona, Spain. spuig@esteve.es
Moragon
T
T
García-Soret
A
A
Martínez
L
L
D000818:Animals; D000928:Antidepressive Agents / Q000097:blood* / Q000493:pharmacokinetics; D002849:Chromatography, Gas / Q000379:methods*; D004285:Dogs; D011720:Pyrazoles / Q000097:blood* / Q000493:pharmacokinetics; D051381:Rats; D012015:Reference Standards; D012680:Sensitivity and Specificity
C427705:5-(alpha-(2-(dimethylamino)ethoxy)-2-thienylmethyl)-1-methyl-1H-pyrazole; C427704:5-(alpha-(2-(methyamino)ethoxy)-2-thienylmethyl)-1-methyl-1H-pyrazole; D000928:Antidepressive Agents; D011720:Pyrazoles