A sensitive determination method for mexiletine derivatized with dansyl chloride in rat plasma utilizing a HPLC peroxyoxalate chemiluminescence detection system.
A sensitive determination method for a non-fluorescent anti-arrhythmic drug, mexiletine, in rat plasma is presented utilizing a HPLC peroxyoxalate chemiluminescence (PO-CL) detection system. After an internal standard (4-methylmexiletine, 4.35 pmol) and 0.1 N sodium hydroxide solution were added to 5 microL rat plasma, the solution was poured onto an Extrelut 1 column. Both mexiletine and the internal standard were eluted with diethy ether and then the eluate was evaporated to dryness. The residue was dissolved in 0.2 M borate buffer (pH 8.5) and mixed with dansyl chloride (75 nmol) in acetronitrile. After standing of 90 min at room temperature, 0.5 N HCl was added to the reaction mixture to stop the reaction and a 2/45 aliquot of the mixture was subjected to a HPLC PO-CL detection system using bis(4-nitro-2(3,6,9-trioxadecyloxycarbonyl)phenyl) oxalate (TDPO) and hydrogen peroxide. The calibration curve for mexiletine in rat plasma was linear over the range 20-100 ng/mL plasma (20.6-103 fmol/injection). The detection limit (S/N = 2) was 1.0 fmol over the whole procedure. The method was applied to the measurement of the time courses of plasma mexiletine concentration after oral administration of the drug [25 mg (115.9 mumol)/kg] to rats.
Nishitani
A
A
Branch Hospital Pharmacy, University of Tokyo, Japan.
Kanda
S
S
Imai
K
K
D000818:Animals; D002851:Chromatography, High Pressure Liquid; D003619:Dansyl Compounds / Q000032:analysis; D005260:Female; D006863:Hydrogen-Ion Concentration; D008163:Luminescent Measurements; D008801:Mexiletine / Q000097:blood*; D010070:Oxalates; D051381:Rats; D011919:Rats, Inbred Strains
D003619:Dansyl Compounds; D010070:Oxalates; D008801:Mexiletine; C044622:peroxyoxalate