animal article unclassified drug Animals 160 nonhuman 143 metabolism 127 controlled study 116 animal cell 82 priority journal 72 animal experiment 71 human 68 mouse 68 Mice 64 physiology 63 genetics 62 Humans 61 chemistry 59 drug effect 52 animal tissue 47 Rats 45 rat 45 messenger RNA 44 protein expression 42 male 40 female 39 Male 38 Female 35 animal model 35 in vitro study 34 RNA, Messenger 32