This study will include both a single dose session and a multiple dose session. In the single dose session, patients will be randomized to receive a single oral dose of either XTL 2125 or placebo on Day 1, in a dose-escalating design, followed by a multiple dose session that will start on day 8 and will continue for 14 days. The same patients will receive XTL 2125 three times daily at the same dose administered in the single dose session.