<qa>  What is the main method of contraception?8. Women of childbearing potential must have a negative serum pregnancy test before study entry. Both men and women must agree to use a medically acceptable method of contraception throughout the treatment period and for 6 months after discontinuation of treatment. Acceptable methods of contraception include: intrauterine conceptive device IUD, oral contraceptives, subdermal implant and double barrier condom with a contraceptive sponge or contraceptive suppository. 