Article 339 human 281 controlled study 279 Humans 224 nonhuman 213 enzyme activity 175 metabolism 174 unclassified drug 160 male 159 enzyme linked immunosorbent assay 140 female 133 chemistry 112 Enzymes 108 Male 103 adult 99 Animals 97 Female 92 genetics 91 animal 90 animal experiment 77 human cell 68 protein expression 66 drug effect 64 enzyme 63 major clinical study 63 middle aged 63 animal model 59 Middle Aged 56 animal tissue 56 rat 55