- Previously enrolled in B1321001 for at least 4 weeks.
- Previously enrolled in B1321003, discontinued from the study.
- Completed the B1321003 study as planned.
- Treated with an investigational drug (other than sitaxsentan or sildenafil in either
B1321001 or B1321003) or device that has not received regulatory approval within the
30 days prior to Baseline/Day 1 or during the study.