The effects of poloxamer and HPMC on the dissolution rate of felodipine were investigated and a felodipine controlled release tablet was developed by increasing the water solubility of felodipine and using swelling polymer to control release rate. Milling of felodipine slightly increased the dissolution rate of felodipine when compared with physical mixture. XRD results indicated that felodipine remained in the crystalline form even after co-milling with poloxamer. Improved dissolution rates after co-milling with HPMC and poloxamer were due to both solubilization effect of polymer and milling. The effect of poloxamer on dissolution rate was more significant than that of HPMC. Based on increased solubility of felodipine in the presence of poloxamer, it was concluded that the improved dissolution rate of felodipine was mainly due to a high local concentration of poloxamer around felodipine. Controlled release felodipine tablets were prepared using poloxamer as a solubilizing agent and Carbopol as a controlled release matrix.
BackgroundPlant extracts are a reservoir of pharmacologically active substances; however, conventional analytical methods can analyze only a small portion of an extract. Here, we report a high-throughput analytical method capable of determining most phytochemicals in a plant extract and of providing their molecular formulae from a single experiment using ultra-high-resolution electrospray ionization mass spectrometry (UHR ESI MS). UHR mass profiling was used to analyze natural compounds in a 70% ethanol ginseng extract, which was directly infused into a 15 T Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer for less than 10 min without a separation process.ResultsThe UHR FT-ICR MS yielded a mass accuracy of 0.5 ppm and a mass resolving power (m/Δm) of 1,000,000–270,000 for the range m/z 290–1,100. The mass resolution was sufficient to resolve the isotopic fine structure (IFS) of many compounds in the extract. After noise removal from 1,552 peaks, 405 compounds were detected. The molecular formulae of 123 compounds, including 33 ginsenosides, were determined using the observed IFS, exact monoisotopic mass, and exact mass difference. Liquid chromatography (LC)/FT-ICR MS of the extract was performed to compare the high-throughput performance of UHR ESI FT-ICR MS. The LC/FT-ICR MS detected only 129 compounds, including 19 ginsenosides. The result showed that UHR ESI FT-ICR MS identified three times more compounds than LC/FT-ICR MS and in a relatively shorter time. The molecular formula determination by UHR FT-ICR MS was validated by LC and tandem MS analyses of three known ginsenosides.ConclusionsUHR mass profiling of a plant extract by 15 T FT-ICR MS showed that multiple compounds were simultaneously detected and their molecular formulae were decisively determined by a single experiment with ultra-high mass resolution and mass accuracy. Simultaneous molecular determination of multiple natural products by UHR ESI FT-ICR MS would be a powerful method to profile a wide range of natural compounds.
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