Physicochemical Characterization of Lapachol

The aim of this study was to characterize three batches of lapachol (LAP), in order to establish specifications for the development of pharmaceutical forms. Physical methods including nuclear magnetic resonance (H and C NMR), infrared spectroscopy (IR), scanning electron microscopy (SEM), x-ray diffraction, differential scanning calorimetry (DSC), determination of the melting range and drug assay were performed. All batches exhibited assays values that were statistically equal to the chemical reference substance (CRS). Furthermore, we found that lots evaluated had a mean purity value of 99.79%. The DSC curves for the three batches and CRS show an endothermic event in the range of 139.87 to 141.01°C. The IR and NMR spectra of all lots are overlapping. All diffraction profile results showed a series of intense and well-defined diffraction peaks, displaying the typical pattern of a compound with a crystal habit. SEM photographs showed that the crystals present stratified plates with visible separation between the layers. This study was fundamental for the gathering of information on the physical, physicochemical and thermal characteristics of lapachol. Thus, facilitating the monitoring of drug quality of LAP, given it is not yet described in official compendia.