Rapid and direct concentration range judgment of lamotrigine in plasma by the multi test lines with different detection limits on the same lateral flow strip.

Continuous and interval monitoring of target drug concentration is of great importance for the effective and controllable therapy of diseases. In this research, the colloidal gold labeled lateral flow strip (LFS) is utilized for rapid and direct judgement of lamotrigine (LTG) concentration range, a specific medicine for epilepsy with the effective therapeutic concentration from 2.5 to 15 μg/mL in serum (corresponding to 25-150 ng/mL after 100-time dilution). Interestingly, two test lines of different detection limits on the same LFS can show different optical signal intensities at the same concentration of LTG in serum. Therefore, for concentration range judgment, it can be directly judged by the combination results of the two test lines on the same LFS without aid of any instruments. Typically, just with the dilution treatment of serum samples for 100 times, three concentration ranges including 0-25 ng/mL, 25-150 ng/mL, and higher than 150 ng/mL can be easily distinguished by the different test line combination results on the same LFS. The clinical serum samples at different concentrations of LTG have also been successfully measured with this multi detection limits LFS, which is 100% consistent with those of the HPLC. The simple operation and judgement standards of LFS with multi detection limits will make the home-test or self-test of therapeutic drug monitoring possible.