5. Females of childbearing potential who are sexually active must be using an acceptable method of contraception for a period of at least one month before the first dose of study medication, continuing through the duration of the study and for one month after the end of the study. Acceptable birth control methods are: surgical sterilization, oral or implanted contraceptive therapy, intrauterine devices and double barrier methods (diaphragm with spermicidal gel or foam or condoms with contraceptive gel or foam). Post-menopausal is defined as >12 months since last menses. Females who are abstinent may participate if they agree to use a double-barrier method of contraception throughout the study should they become sexually active. .