Omparing two drugs. makers of generic drugs must show that they do not differ significantly from the “reference” drugs that they imitate. one aspect in which drugs might differ is their extent of absorption in the blood. table 20.5 gives data taken from 20 healthy nonsmoking male subjects for one pair of drugs.33 this is a matched pairs design. numbers 1 through 20 were assigned at random to the subjects. subjects 1 through 10 received the generic drug first, followed by the reference drug. subjects 11 through 20 received the reference drug first, followed by the generic drug. in all cases, a washout period separated the two drugs so that the first had disappeared from the blood before the subject took the second. by randomizing the order, we eliminate the order in which the drugs were administered from being confounded with the difference in the absorption in the blood. do the drugs differ significantly in the amount absorbed in the blood?