controlled study Article 200 human 135 nonhuman 131 Humans 111 male 96 metabolism 94 unclassified drug 89 female 79 enzyme linked immunosorbent assay 67 adult 66 protein expression 66 animal experiment 59 Male 58 enzyme activity 56 genetics 55 Female 53 human cell 53 Animals 50 animal 45 animal model 45 major clinical study 45 middle aged 45 animal tissue 44 chemistry 42 Middle Aged 40 animal cell 40 gene expression 38 mouse 37 drug effect 36