8. Sexually active women of childbearing potential must be using a medically acceptable method of birth control and have a negative qualitative serum beta-human chorionic growth hormone (beta HCG) pregnancy test result from a blood sample collected at the initial screening visit. A woman of childbearing potential is defined as a female who is biologically capable of becoming pregnant. A medically acceptable method of birth control includes intrauterine devices in place for at least 3 months, surgical sterilization, or adequate barrier methods (e.g., diaphragm and foam). An oral contraceptive alone is not considered adequate for the purpose of this study. Use of oral contraceptives in combination with another method (e.g., a spermicidal cream) is acceptable. In subjects who are not sexually active, abstinence is an acceptable form of birth control and qualitative serum βHCG pregnancy tests must be tested per protocol.