<qa>  What is the subject of a negative serum pregnancy test?7. The subject, if female and of child-bearing potential not 2 years post-menopausal or surgically sterilized, must have a negative serum pregnancy test at Screening Visit 1 and be willing to avoid pregnancy and practice adequate birth control from the time of study enrollment until 30 days after the last dose of study medication. Adequate methods of birth control are: oral contraception, intrauterine device, implantable contraceptive device, depot contraceptive, or a barrier method plus spermicide. Additional serum pregnancy tests will be administered at Visit 6, Visit 8, and Visit 9. 