A judge in the US state of Delaware has granted a request by Valeant Pharmaceuticals International and Pershing Square Capital Management, the investment vehicle of activist shareholder Bill Ackman, for expedited proceedings in a dispute over a special meeting dispute with Botox manufacturer Allergan.

Andre Bouchard of Delaware's Court of Chancery has scheduled a three-day trial to start Oct. 6. Allergan had proposed a Nov. 24 trial.

Allergan is the subject of a $52 billion takeover attempt spearheaded by Ackman. The investor is seeking the meeting to try to replace the bulk of Allergan board members with his own slate of directors.