18. Women of childbearing potential must have a negative serum pregnancy test within 72 hours prior to receiving the first dose of study medication. Both women and men must agree to use a medically acceptable method of contraception throughout the treatment period and for four months after discontinuation of treatment. Acceptable methods for contraception include intrauterine device, oral contraceptive, subdermal implant and double barrier. Subjects of childbearing potential are those who have not been surgically sterilized or have not been free from menses for ≥ 1 year