The primary objective of the study is to estimate the effects of different strong enzyme (CYP3A4) inhibitors, itraconazole, diltiazem, or verapamil on the single dose pharmacokinetics of PF-00489791 in healthy volunteers. The study will enroll approximately 18 subjects that are randomized to 1 of 3 treatment groups. The study is also intended to determine the safety and tolerability of single-dose PF- 00489791 when it is administered with steady-state itraconazole, diltiazem, or verapamil.