After the U. S Patent and Trademark Office (PTO) was asked by the central court to reassess its decision to deny extension of the patent for Medicines Co.'s anti-clotting drug, Angiomax, there was a rise in the company's shares by 27 percent.

However, the application for an extension of the patent was denied by PTO under the Hatch-Waxman Act because it was filed late.

The PTO also had to take orders from the Virginia court for taking quick actions to make sure that the patent does not expire pending resolution of the court proceedings.

RBC analyst Kantor said the court's decision "appears to imply that Medicines can keep its patent alive as long as there is an ongoing proceeding, and the six months of pediatric exclusivity will not kick in until the patent officially expires".

"At a minimum, this could buy Medicines several additional months of exclusivity", he added.

The shares of Medicines Co. were up by 20 percent at $9.93 in midday trade Wednesday on NASDAQ. Earlier during the session, it touched an increase of $10.45.