- Women of childbearing potential must have a negative serum pregnancy test 72 hours prior to study enrollment. Women of childbearing potential and men with partners of childbearing potential must use a highly effective method of contraception throughout the entire study and up to 8 weeks after the last dose of any study drug (including obatoclax maintenance). Effective contraception or birth control is defined as those with a low failure rate (less than 1% per year) when used consistently and correctly.