Inclusion Criteria:

- Subjects who complete 26-week maintenance treatment of the A3921084 study or subjects
who withdraw early due to A3921084 study treatment failure (see Appendix 5).

- Women of childbearing potential must test negative for pregnancy prior to study
enrolment.

- Sexually active females of childbearing potential are required to use adequate
contraceptive methods during the study period and until completion of the follow-up
procedures. No specific contraceptive measures are required in male subjects during
study participation.

Exclusion Criteria:

- Subjects who have been discontinued due to protocol violation(s) (as determined by
the Sponsor) in the A3921084 study.

- Subjects who were discontinued from the A3921084 study due to an adverse event.

- Subjects likely to require any non-elective surgery or surgery requiring overnight
stay (with the exception of minor same day outpatient procedures that will not
interfere with study drug dosing).