Rapid HPLC-F analysis of agomelatine in dried blood spots after microwave-assisted extraction

Agomelatine (N-[2-(7-methoxynaphthalen-1-yl)ethyl]acetamide) is a new antidepressant drug with a chemical structure similar to that of melatonin, which contains an indole part, whereas agomelatine has a naphthalene bioisostere instead. Agomelatine acts as an agonist at melatonin MT1 and MT2 receptors; furthermore, it is antagonistic to serotonin 5-HT2C and 5-HT2B receptors that are closely involved in the pathophysiology of depression. This combined action may explain the antidepressant effect of agomelatine and its efficacy in generalized anxiety disorder. In order to optimize the dosage in the patient and to avoid side effects of the drug due to an incorrect dose or to drug-drug interactions, it is important to have at disposal reliable analytical methods for the evaluation of blood levels of agomelatine. The aim of this work is the development of a rapid chromatographic method for the analysis of agomelatine in dried blood spot (DBS) specimens. An HPLC method coupled with a spectrofluorometric detector has been developed, exploiting the native fluorescence of the molecule. Chromatographic conditions were optimized using as stationary phase a C8 column and a mobile phase consisting of a mixture of neutral phosphate buffer and acetonitrile. The analyte was extracted from DBSs by suitable solvent microwave-assisted extraction and, then, injected into HPLC system. Preliminary results are promising and the method is undergoing validation in terms of extraction yield, linearity and precision.