This is an open-label, randomized, 2-period crossover, inpatient study to be performed in healthy subjects. The study will consist of 2 treatment periods: There will be 2 parallel cohorts of 12 subjects each who will be enrolled to receive single doses of tolbutamide or AGG-523 plus tolbutamide in periods 1 and 2 in a crossover design. Doses of test article will be administered after an overnight fast of at least 10 hours.