In a move that saw Repros Therapeutics Inc shares jump 44%, the U. S. health regulator has lifted the full clinical hold on the company's lead drug Proellex, used to treat uterine fibroids.

Now, the Food and Drug Administration's clinical hold would be partial. Therefore, Repros has got the green signal to go ahead with a single study on the drug, which has been hinted to reduce menstrual bleeding associated with uterine fibroids and endometriosis.

Notably, the FDA had stalled clinical study on the drug following fear about its effects on the liver of patients about a year ago.

Not ready to arrive at a conclusion regarding the success of the study as of now, analyst Matthew Kaplan said: "It's difficult to predict and that's why they have to go through the test to establish the correct doses".

The new low-dose study, it has been learnt, would aim at achieving both safety and efficacy. During the course, five different doses of Proellex would be tested. To begin with, 1 mg of dose would be given, with researchers not ready to administer higher doses till they are too sure about its safety.

In its earlier study, Repros claimed, toxicity was experienced due to higher doses. But this time, it said, tests would be conducted outside the range where toxicity was witnessed earlier.