- Female subjects showing positive results on a serum pregnancy test before the study, and those who were of childbearing potential agreed to use one of the following medically accepted methods of contraception during the entire period of the study: abstinence, documented tubal ligation at least 1 year before enrollment in the study, documented placement of an intrauterine device with a proven failure rate of <1% per year, or double barrier methods (a spermicide plus a male condom or female diaphragm).