Inclusion Criteria:

• Eligible subjects who completed assessments for the final visit of the previous controlled trials and who signed appropriate informed consent are eligible to enroll in this extension study.
• If a female of childbearing potential, the subject must agree to continue practicing an acceptable method of birth control (i.e., surgical sterilization, approved hormonal contraceptives, barrier methods [such as a condom or diaphragm] used with a spermicide, or an intrauterine device).

Exclusion Criteria:

• Have had any change in clinical status that, in the opinion of the Investigator, would pose a safety risk for participation in this extension study;
• Have been found to be unable to complete study assessments in the previous controlled trial;
• Have prematurely discontinued study drug during the previous study