Study to Evaluate Drug-Drug Interaction Between Valopicitabine and Ribavirin <A HREF="http://www.clinicaltrials.gov/ct/show/NCT00395421;jsessionid=C334253D7A0469141B0ADC61373D3D40?order=.." target="_blank">http://www.clinicaltrials.gov/ct/show/NCT00395421;jsessionid=C334253D7A0469141B0ADC61373D3D40?order=...</A>.