<qa>  How many subjects were randomly assigned to 3 dose groups?The study of single-dose was randomized, three-period, crossover. And in this study, 12 subjects were randomly assigned to 3 dose groups and received a single dose of 10mg, 20mg and 40mg lafutidine tablets. The washout period was 7 calendar days. In the multiple-dose, 12 subjects took lafutidine tablets of 10 mg twice a day for 6 consecutive days. In the food-effect study, 12 subjects were randomly assigned to 2 groups. One group received a single dose of 10mg lafutidine tablets under fasted condition, while the other were in fed condition. The drug administrations were separated by a wash-out period of seven calendar days. In each study group, the male and the female are both in half of the subjects. Using a liquid chromatography tandem mass spectrometry LCMSMS method to determine the plasma concentration of lafutidine. Pharmacokinetic parameters were calculated using the single compartment model. 