机器人药片有望给糖尿病患者带来福音

    近日，《华尔街日报》（the Wall Street Journal ）刊登的一篇文章为我们介绍了一种独特的“机器人药片”。它可以用来取代胰岛素针剂之类的注射类药物，减轻糖尿病等慢性病患者用药的痛苦。

    目前这种机器人药片尚未进行人体测试。《华尔街日报》指出，机器人药片要获得联邦批准至少还得一年的时间，但是它已经赢得了很多支持者。比如硅谷的一家名叫InCube Labs的初创公司正在进行相关研发工作，谷歌创投（Google Ventures）为这个项目提供了早期投资，另外，２５００多万名美国糖尿病患者也在翘首期盼这种药物早日面世。

    但是机器人药片也存在竞争对手。去年１２月，以色列的Oramed制药公司宣布它一种尚处于试验阶段的口服胰岛素药片取得了积极的成果，一项研究“清楚地表明”，这种药物是“安全的，而且耐受力良好。”之后这家公司的股价由６美元飙升到了３２美元。但是不久后被曝出，这个结论的基础只是一项仅仅为期一个礼拜的测试，而且被试者只有３０人。随后这家公司的股票立即跌回原形。

    自从９０多年前，一个加拿大医生团队发现了胰岛素以来，大家一直没有放弃过寻找胰岛素的替代物，或者至少是一种替代性的给药方法。胰岛素虽然在治疗糖尿病上有效，但它也有自己的缺点。

    胰岛素就像汉堡包一样，是一种蛋白质，因而在口服用药中难免被分解和破坏。早在上世纪２０年代，人们就采用了注射的方式使用胰岛素，每次注射完毕后都要对注射器和针头进行消毒。早期的胰岛素药效持续的时间较短，而针头在重复使用的过程中会变得越来越钝，因此注射胰岛素时的痛苦自不待言。

    早在１９２５年，人们就开始尝试用其他方法摄取胰岛素，但是直到现在，这种做法依然存在很高风险。胰岛素的并发症从失明、肾衰竭、足病（甚至截肢）到心血管疾病不一而足。更令人担忧的是，肥胖和缺乏锻炼使糖尿病的发病率呈稳步上升之势。据美国疾病预防控制中心（to the Centers for Disease Control and Prevention）统计，超过４０%的美国人要么已经被诊断为糖尿病，要么就是前驱糖尿病（也就是虽未达到II型糖尿病标准，但存在葡萄糖代谢障碍），而且糖尿病人的数量正像传染病一样越来越多。

    过去９０年里，不时也会涌现出胰岛素针剂的替代品，但都只是昙花一现。有效、给药方便、同时经济实惠的替代品直到现在也没有被开发出来。

    为了寻找其它的给药方法，可以说科学家们已经把人体的里里外外试了个遍。尽管人体大多数部位都不适合胰岛素的给药，但是科学家们还是在执著地探索着人体的每个面、膜、腔的给药可能性。下面仅列举这些年来的一些研究，排名不分先后。

    阴道。数据显示，胰岛素可以通过阴道壁吸收，但是效率较低，况且它在伦理上也不是一种可以接受的方法。

    直肠。直肠内壁也是一个很好的脉管组织，可以吸收很多药物。但是很显然它的局限性也使它不太可能用于日常用药。

    A recent article in the Wall Street Journal provided a fascinating description of arobotic pill designed to replace injectable drugs like insulin that are used to treat chronic conditions like diabetes.

    The robotic pill hasn't been tested in humans, and the Journal pointed out that it is at least a year away from even seeking federal approval, but a lot of people are rooting for it. They include InCube Labs, a Silicon Valley startup that's doing the development work; Google Ventures (GOOG), which has provided early financing; and the more than 25 million Americans who currently suffer from diabetes.

    The robot has competition. The shares of one would-be competitor -- an Israeli company named Oramed Pharmaceuticals (ORMP) -- soared from $6 to $32 in December when it reported positive results for an experimental insulin pill, citing a study that "clearly shows" that the drug "is safe and well-tolerated." The stock gave back most of the gains when it turned out that results were based on a one-week test of 30 patients.

    Here's the thing. Everyone and his brother have been looking for a substitute for -- or an alternate way to deliver -- insulin, almost from the day it was discovered by a team of Canadian doctors more than 90 years ago. It does the job, but it has drawbacks.

    Insulin is a protein, like hamburgers, and as such is digested and destroyed when swallowed. Back in the 1920s, it was injected using a glass syringe with a steel needle that had to be sterilized after every use. Early insulin was short-acting, reusable needles were never as sharp as during their first use, and injections were painful. It was a brutal, unsophisticated experience.

    As early as 1925, attempts were made to find other ways to get insulin into the body. Then as now, the stakes were high: Complications from diabetes range from blindness and kidney failure to limb loss and cardiovascular disease. To make things worse, the lack of exercise and growing obesity are fueling a steady increase in diabetes. According to the Centers for Disease Control and Prevention, more than 40% of the U.S. population has either clinical diabetes or prediabetes, and the numbers are growing at what the CDC calls epidemic proportions.

    Substitutes for insulin injections have regularly appeared during the past 90 years, but so far an acceptable answer -- one that is effective, easily delivered and economically feasible -- has not been developed.

    The search for alternative delivery routes has involved the entire body. Although inhibitors at most sites preclude their use for insulin, every surface, membrane, and cavity has been explored as a possibility. In no special order, here are a few that have been studied over the years:

    Vagina.Data show that insulin can be absorbed through the vaginal wall, but it's an inefficient and socially unacceptable method.

    Rectum.The rectal lining is a good vascular tissue and will absorb many drugs, but obvious limitations make this site unlikely for regular daily use.