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片剂是最常用的剂型之一,但药物吸收较慢且不够完全。因为其中的药物已被紧压,服后在胃肠液中溶解缓慢,故有时疗效不够理想。一般认为,片剂的崩解度对于药物吸收有一定关系。但是,崩解快的并不一定就是吸收好的。例如,有人发现,两种泼尼松片,崩解都快,都只有两分半钟,但 A 片疗效好,B 片疗效差。细加研究,发现 A 片中药物较之 B 片中药物容易溶解出来:如果以溶出标示量50%的药物所需的时间来表示,A 片仅为4.3分钟,而 B 片竟长达173分钟!又如两种甲苯磺丁脲片,A 片2分钟崩解,3.8分钟溶出,疗效好,B 片崩解时间为 A 片的两倍,溶出时间长达103分钟,疗效只有 A 片的1/3.5。这两个例子都说明了,对于难溶性药物而言,溶出速度(Dissolution rate)较之崩解度更能反映出片剂的吸收情况。为什么呢?因为崩解度只说明药片崩解为
Tablets are one of the most commonly used dosage forms, but drug absorption is slow and not complete. Because of which the drug has been squeezed, after serving slowly dissolved in gastrointestinal fluids, so sometimes the effect is not ideal. It is generally believed that the degree of disintegration of the tablet has a relationship to the absorption of the drug. However, disintegration is not necessarily fast absorption. For example, it was found that both prednisone tablets disintegrated rapidly, only two and a half minutes, but A good effect, B poor efficacy. A closer study found that the drug in tablet A was more soluble than the drug in tablet B. If the time required to dissolve 50% of the labeled drug was indicated, tablet A was only 4.3 minutes and tablet B was as long as 173 minutes Another example is the two tolbutamide tablets, A tablet disintegration 2 minutes, 3.8 minutes dissolution, good effect, B tablets disintegration time for the A-chip twice, the dissolution time of up to 103 minutes, the efficacy of only A slice of 1 /3.5. Both of these examples illustrate that, for poorly soluble drugs, the dissolution rate reflects the absorption profile better than the disintegration rate. Why? Because the disintegration only shows the tablet collapsed to