Blood samples were drawn immediately before taking the drug , then at 20 and 40 minutes , and 1 , 1.5 , 2 , 2.5 , 3 , 4 , 5 , 6 , 8 , 10 , 12 , 15 , and 24 hours after dosing , to evaluate pharmacokinetic parameters of the single dose administration , ie , the area under the plasma concentration-time curve ( AUC ) from time zero to 24 hours ( AUCt ) , AUC from time zero to infinity ( AUC ( inf ) ) , the peak plasma concentration of the drug ( Cmax ) , time needed to achieve Cmax ( tmax ) , and the elimination half-life ( t1/2 ) .