5. Male subjects who are partners of women of childbearing potential must use a condom plus spermicide and their female partners if of childbearing potential must use a highly effective method of contraception (see methods described in Inclusion Criterion No. 4) beginning at least one menstrual cycle prior to starting study drug, throughout the entire study period, and for 30 days after the last dose of study drug, unless the male subjects are totally sexually abstinent or have undergone a successful vasectomy with confirmed azoospermia or unless the female partners have been sterilized surgically or are otherwise proven sterile (see Inclusion Criterion No.4).