In vitro and in vivo investigation of dexibuprofen derivatives for CNS delivery

Aim： Dexibuprofen, the S（＋）-isomer of ibuprofen, is an effective therapeutic agent for the treatment of neurodegenerative disorders. However, its clinical use is hampered by a limited brain distribution. The aim of this study was to design and synthesize brain-targeting dexibuprofen prodrugs and to evaluate their brain-targeting efficiency using biodistribution and pharmacokinetic analysis. Methods： In vitro stability, biodistribution and pharmacokinetic studies were performed on male Sprague-Dawley rats. The concen- trations of dexibuprofen in biosamples, including the plasma, brain, heart, liver, spleen, lung, and kidney, were measured using high pressure lipid chromatography （HPLC）. The pharmacokinetic parameters of the drug in the plasma and tissues were calculated using obtained data and statistics. Results： Five dexibuprofen prodrugs that were modified to contain ethanolamine-related structures were designed and synthesized. Their chemical structures were confirmed using 1H NMR, ^13C NMR, IR, and HRMS. In the biodistribution study, 10 min after intravenous administration of dexibuprofen （11.70 mg/kg） and its prodrugs （the dose of each compound was equivalent to 11.70 mg/kg of dexibu- profen） in male Sprague-Dawley rats, the dexibuprofen concentrations in the brain and plasma were measured. The Cbrain/Cpfasma ratios of prodrugs 1, 2, 3, 4, and 5 were 17.0-, 15.7-, 7.88-, 9.31-, and 3.42-fold higher than that of dexibuprofen, respectively （P〈O.01）. Thus, each of the prodrugs exhibited a significantly enhanced brain distribution when compared with dexibuprofen. In the pharmacoki- netic study, prodrug I exhibited a brain-targeting index of 11.19 {DTl=（AUCbrain/AUCplasrna）3/（AUCbrain//AUCplasrna）dexibuprofen}. Conclusion： The ethanolamine-related structures may play an important role in transport across the brain blood barrier.