Development of a stability-indicating assay method by HPLC-DAD and MS characterization of forced degradation products of ravuconazole.

Ravuconazole (RAV) is a triazole antifungal with broad spectrum and a novel alternative in the treatment of systemic fungal infections. A stability-indicating method by high-performance liquid chromatography-diode array detection was developed and fully validated to assay ravuconazole in the presence of its degradation products. Separation was achieved with a Sunfire C18 column (250 mm × 4.6 mm id, 5 µm), mobile phase composed of acetonitrile and water (80:20), at 1 mL/min. The volume of injection was 5 µL and DAD detection was performed at 287 nm. RAV was well resolved from its degradation products and the method proved to be linear, selective, accurate, precise and robust. A forced degradation study was conducted on the pure drug under oxidative conditions in presence of H2O2 and metallic ions and under acid, alkaline and neutral hydrolysis. RAV was degraded mainly under alkaline hydrolysis, forming two main degradation products. The chemical structures were proposed according to the data obtained by liquid chromatography coupled to mass spectrometry (LC-MS) analysis. This study provided a new and selective stability-indicating method to evaluate the intrinsic stability of ravuconazole in active pharmaceutical ingredients. The developed method was found to be suitable for quality control routine analysis and to stability studies of ravuconazole.

Development and validation of an LC-ESI-MS/MS method for the simultaneous quantification of naproxen and sumatriptan in human plasma: application to a pharmacokinetic study.

A sensitive and fast liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) method was developed and validated for the simultaneous quantification of naproxen and sumatriptan in human plasma. A simple liquid-liquid extraction procedure, with a mixture of ethyl acetate, methyl tert-butyl ether, and dichloromethane (4:3:3, v/v), was used for the cleanup of plasma. Naratriptan and aceclofenac were employed as internal standards. The analyses were carried out using an ACE C18 column (50 × 4.6 mm i.d.; particle size 5 µm) and a mobile phase consisting of 2 mM aqueous ammonium acetate with 0.025 % formic acid and methanol (38:62, v/v). A triple-quadrupole mass spectrometer equipped with an electrospray source in the positive mode was set up in the selective reaction monitoring mode to detect the ion transitions m/z 231.67 → m/z 185.07, m/z 296.70 → m/z 157.30, m/z 354.80 → m/z 215.00, and m/z 336.80 → m/z 97.94 for naproxen, sumatriptan, aceclofenac, and naratriptan, respectively. The method was validated and proved to be linear, accurate, precise, and selective over the ranges of 2.5-130 µg mL(-1) for naproxen and 1-50 ng mL(-1) for sumatriptan. The validated method was successfully applied to a pharmacokinetic study with simultaneous administration of naproxen sodium and sumatriptan succinate tablet formulations in healthy volunteers.