4. Male and female patients will be eligible for enrollment. Females should be either of non-childbearing potential by reason of surgery, radiation, menopause (one year post onset), or of childbearing potential and practicing a medically acceptable method of contraception (eg, abstinence, a barrier method plus spermicide, or IUD) for at least one month before study randomization and for two months after the end of the study, and have a negative serum B-hCG at Screening. Pregnant and/or lactating females are excluded. Those women using hormonal contraceptives must also be using an additional approved method of contraception (eg, a barrier method plus spermicide, or IUD) starting with the Baseline Phase and continuing throughout the entire study period.