Animals animal 192 chemistry controlled study nonhuman 174 metabolism 132 unclassified drug 112 priority journal 102 Article 96 article 92 human 90 Humans 88 animal cell 80 animal experiment 58 female 56 genetics 54 mouse 54 animal tissue 52 Mice 50 drug effects 48 human cell 48 male 46 Male 42 in vitro study 42 physiology 42 Female 40 drug effect 40 rat 36 protein expression 34 Rats 32