4. All females must have a negative serum beta human chorionic gonadotropin (B- hCG) test result at Screening and negative urine B-hCG test result at each Baseline. Females of child-bearing potential must agree to use 2 medically acceptable methods of contraception (eg, abstinence where this is the subject's preferred lifestyle, a non-hormonal intrauterine device, a double-barrier method such as condom + spermicide or condom + diaphragm with spermicide, or have a vasectomized partner with confirmed azoospermia) throughout the entire study period and for 4 weeks after study drug discontinuation. The only subjects who will be exempt from this requirement are postmenopausal women (defined as at least 12 months consecutive amenorrhea, in the appropriate age group, without other known or suspected primary cause) or subjects who have been sterilized surgically or who are otherwise proven sterile (ie, bilateral tubal ligation with surgery at least 1 month prior to dosing, hysterectomy, or bilateral oophorectomy with surgery at least 1 month prior to dosing);