On Monday, the shareholders at Elan approved a share buyback. This would mean that the US based Royalty Pharma's hostile bid for Elan will lapse. A legal challenge should be sought after a legal challenge filed succeeds.

Royalty Pharma hoped to convince Elan's owners to accept its bid amid opposition from its target's board.

Last month, Royalty made its conditional takeover offer on shareholders rejecting other four resolutions at a meeting on Monday. Last week, it had won an Irish court injunction against a regulator. The injunction allowed it to appeal against a ruling that it cannot change the attached conditions to its offer.

Shareholders rejected Elan's proposed US$1 billion deal with Theravance Inc. purchase of a private drug firm. Elan put itself up for sale on Friday.

The current offer from Royalty is at US$13 per share with a contingent value right clause that could add US$2.50 per share once its blockbuster drug reached sales milestone.