Abstract

ANALYTICAL METHOD FOR THE QUANTIFICATION OF CAPSAICIN IN HUMAN PLASMA BY HIGH-RESOLUTION LIQUID CHROMATOGRAPHY

Dr. Gilberto Quiñonez Palacio*, QFB David Vargas Torres, M.C. Lizbeth Mariela Cerón Ramírez, Dra. María de los Angeles Leal

ABSTRACT

In industrialized countries, diabetes is the most common cause of neuropathy. The physiopathology base is a distal axonopathy with predominant sensory, autonomic manifestations. There has been remarkable progress in controlling pain associated with diabetic neuropathy, which sometimes is of high intensity and does not respond to usual measures. Several studies have been conducted with capsaicin as an analgesic20,21. The administration by oral form and in the form of instillation have been increasing the evidence as an effective analgesic53. Reason why we should look for alternatives with active ingredients such as capsaicin which has a mechanism of action very accurate by the depletion of neuropeptides intimately associated with the transmission of pain. We used a method of high-resolution liquid chromatography with a fluorescence detector for the assessment of concentrations for capsaicin Using capsaicin as primary standard USP and sodium naproxen as a secondary standard (internal standard). The mobile phase was composed of water, acetonitrile, tetrahydrofuran and 0.1% formic acid. A fluorescence detector was used for the detection of capsaicin. The approximate retention time was for capsaicin 6 minutes and sodium naproxen in 4 minutes. The analytes were recovered by extraction with Isobutil Metil-Ketone and a pH 7.0 phosphate Buffer, using a CIS column of 3.9 x 150 mm 5 mg with a flow of 1ml per min. Using a proportion of phase of water-acetonitrile-tetrahydrofuran-monobasic potassium phosphate mobile pH 2.5 (55:40:5: 1). The concentrations of capsaicin were monitored in the fluorescence detector to a length of 275 excitation and emission 305nm. The method was evaluated by a number of features of a validation (selectivity, accuracy, repeatability and intermediate precision, limit of detection, limit of quantification and a range of calibrations). The method was linear (r2 = 0.9999), straight (CV = 0.26) and Reproducible (CV. 0.72 inter-days and different analyst) and proved to be robust in the changes, coefficients of variation less than 3.0%. Based on the results of each performance parameter it passes the validation for the assessment of concentrations for capsaicin in human plasma.

Keywords: capsaicin, fluorescence detector, phosphate buffer, high resolution.