In March 2006, the FDA recommended an approvable status to sitaxentan but said it would not yet approve the product. In July 2006, sitaxentan received a second approvable letter stating that efficacy outcome issues raised in the context of the STRIDE-2 study were still unresolved. In July 2007, Encysive commenced a formal dispute resolution process in a preliminary meeting with the FDA. In September 2007 the company announced that it was making preparations for another phase III clinical trial (intended to be named STRIDE-5) to overcome the FDA's concerns. The takeover by Pfizer resulted in a reconfiguration and extension of these plans, to include combination therapy with sildenafil. The Sitaxentan Efficacy and Safety Trial With a Randomized Prospective Assessment of Adding Sildenafil (SR-PAAS) was an ongoing program of three clinical trials conducted in the United States (ClinicalTtrials.gov identifiers: NCT00795639, NCT00796666 and NCT00796510) with anticipated completion dates between June 2010 and January 2014.