Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.
Acta Pharmacol Sin. 2013 Oct;34(10):1337-48. doi: 10.1038/aps.2013.86. Epub 2013 Aug 26.
Both Borneolum (Chinese name Bingpian; dextrorotatory borneol) and Borneolum syntheticum (synthetic Bingpian; a mixture of optically inactive borneol and isoborneol) have been used for medicinal purposes in Chinese traditional medicine. The aim of this study was to develop a sensitive assay for measuring volatile ingredients borneol, isoborneol, and their metabolite camphor in pharmacokinetic study of Bingpian.
Rat plasma samples were prepared using liquid-liquid microextraction: 70 μL of plasma sample (containing 125 nmol/L naphthalene as the internal standard) was extracted with 35 μL of n-hexane. The resulting n-hexane extract (20 μL) was introduced into a gas chromatography/mass spectrometry system using programmable temperature vaporizing-based large-volume injection. The assay was validated to demonstrate its reliability for the intended use. Using this assay, pharmacokinetic studies of Bingpian, synthetic Bingpian, and Fufang-Danshen tablets (containing synthetic Bingpian) were conducted in rats.
The extraction efficiency for the analytes and the internal standard from plasma was almost constant with decrease in n-hexane-to-plasma volume ratio, thus enabling a small volume of extracting solvent to be used for sample preparation, and enhancing the assay sensitivity. The lower quantification limit for measuring borneol, isoborneol, and camphor in plasma was 0.98 nmol/L, which was 33-330 times more sensitive than those reported earlier for Bingpian and synthetic Bingpian. The applicability of the miniaturized liquid-liquid extraction technique could be extended to measure other volatile and nonvolatile medicinal compounds in biomatrices, which can be predicted according to the analytes' octanol/water distribution coefficient (logD) and acid dissociation constant (pKa).
This assay is sensitive, accurate and free of matrix effects, and can be applied to pharmacokinetic studies of Bingpian, synthetic Bingpian, and Bingpian-containing herbal products.
天然冰片（右旋龙脑）和合成冰片（由左旋龙脑和异龙脑组成的混合物）在中药中一直被用作药用。本研究旨在开发一种灵敏的分析方法，用于测量龙脑、异龙脑及其代谢产物樟脑在冰片药代动力学研究中的挥发性成分。
采用液液微萃取法制备大鼠血浆样品：70μL 血浆样品（含 125nmol/L 萘作为内标）用 35μL 正己烷提取。所得正己烷萃取物（20μL）采用可编程温度汽化大体积进样技术引入气相色谱/质谱系统。该分析方法经验证，可用于预期用途的可靠性。使用该分析方法，在大鼠中进行了冰片、合成冰片和复方丹参片（含合成冰片）的药代动力学研究。
分析物和内标从血浆中的萃取效率几乎随正己烷与血浆体积比的降低而恒定，因此可以使用小体积的萃取溶剂进行样品制备，并提高分析灵敏度。测量血浆中龙脑、异龙脑和樟脑的定量下限为 0.98nmol/L，比以前报道的冰片和合成冰片的灵敏度高 33-330 倍。微型液液萃取技术的适用性可以扩展到测量生物基质中的其他挥发性和非挥发性药物化合物，这可以根据分析物的辛醇/水分配系数（logD）和酸解离常数（pKa）来预测。
该分析方法灵敏、准确、无基质效应，可应用于冰片、合成冰片和含冰片草药产品的药代动力学研究。
