This is a double blind, dose-ranging study in healthy volunteers. Four sequential dose cohorts of 8 subjects each are planned. Six subjects will be randomly assigned to receive SPI-014 and 2 subjects to receive placebo within each cohort. The doses of SPI-014 will be 1500 mg/day (Group A), 3000 mg/day (Group B), 4500 mg/day (Group C) and 6000 mg/day (Group D), taken orally 3 times a day within 15 min after meals.