[HPLC-fluorescent spectrometric determination of serum mexiletine concentration after derivatization with fluram]

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

Fluram 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.

Mexiletine 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.

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