对大黄后下煎煮方法之疑义
Some doubt about rhubarb decocting method

普遍认为在现代煎煮方法中大黄起泻下作用时应后下，即在第一煎药料即将煎至预定量时，投入同 煎5~10 min。笔者通过重新考证张仲景《伤寒论》原著中含大黄方剂的煎煮方法及现代的化学药理研究，认为大 黄后下煎煮5~10 min的方法并非张仲景原意，大承气汤中“先煎枳、朴，后下大黄，纳芒硝，溶化服”的科学涵 义可能是为避免枳实、厚朴与大黄长时间共同煎煮而削弱其泻下作用。
Rhubarb is generally thought to be decocted for 5-10 min after the other herbs were almost ready, especially when it acts as purgative. Through researching the original prescription containing rhubarbs in Zhang Zhongjing’s Treatise on Febrile Diseases and modern chemical and pharmacological studies, the author found that the general thinking wouldn’t be the best method for decocting rhubarbs. The possible better decocting method for “Da Cheng Qi Decoction” in which rhubarbs play a strong role as purgative is not a short-time decocting but decocting for an enough time and avoiding decocting with citrus and magnolia