drug activity article 106 nonhuman 96 unclassified drug 88 controlled study 74 human 54 Animals 52 priority journal 44 drug synthesis 42 animal cell 40 human cell 40 Humans 38 drug structure 34 in vitro study 32 animal experiment 30 male 28 cytotoxicity 24 drug mechanism 22 mouse 22 Mice 20 Molecular Structure 18 animal model 18 drug screening 18 rat 18 structure activity relation 18 Dose-Response Relationship, Drug 16 IC 50 16 Structure-Activity Relationship 16 Trypanosoma cruzi 16 animal 16