Natural progesterone, the sex hormone¹ used in the first contraceptive pills, is to be tested on patients with severe head injuries.

天然黄体酮，首批避孕药中使用的性激素，被用于治疗有严重脑损伤病人的临床试验中。

Progesterone protects neurons in the brain after an injury

Scientists will begin a phase III clinical trial in March and say the drug could save patients' lives and reduce damage to their brains.

They announced the trial at the annual meeting of the American Association for the Advancement² of Science.

It will involve 1,000 patients in 17 trauma³（外伤 ，创伤） centres across the US.

Dr David Wright, associate professor of emergency medicine at Emory University in Atlanta, will lead the trial.

Complex condition

Previous studies have shown that progesterone（黄体酮） supports the normal development of neurons（神经原，神经细胞） in the brain, and that the hormone has a protective effect on damaged brain tissue.

Dr Wright told BBC News: "Traumatic brain injury is a complex condition - there's swelling⁴（膨胀） , and neuronal death and damage occurring all at the same time.

"The beauty of progesterone is that it seems to work on all of those things."

In earlier tests, the Emory University researchers found that progesterone reduced the risk of death in patients with brain injuries.

Dr Wright hopes that, following this trial, progesterone will become the first drug treatment in 30 years to be approved specifically for severe traumatic brain injury.

Yams

The active ingredient（有效成分，活性成分） , natural progesterone, is very similar to that used in the first contraceptive pills（避孕药） . This has now been superseded⁵（取代，废弃） by a synthetic⁶ progesterone known as progestin. But, for brain injury, only the natural hormone appears to have the desired protective effect.

During the trial, patients with blunt（钝的，生硬的） trauma head injuries will be given an infusion⁷（灌输，浸泡） of natural progesterone that will last for four days. The hormone is extracted from yams（山药，洋芋） - also known as sweet potatoes（番薯，白薯） .

"The dose is probably about three times what would be found in [the blood] of a female in the third trimester（晚期妊娠） of pregnancy," Dr Wright explained.

The US Food and Drug Administration (FDA食品及药物管理局) has made a special allowance for the team to administer the drug without patients' consent（同意，赞成） - so it can be given as soon as possible and have the maximum protective effect.