Article male nonhuman unclassified drug controlled study 68 animal experiment 58 Animals 54 animal 52 Male 48 priority journal 44 mouse 42 metabolism 38 animal cell 36 animal tissue 34 female 34 protein expression 32 animal model 24 drug effects 24 human 24 in vitro study 24 in vivo study 22 physiology 22 Female 20 Mice 20 adult 20 Humans 16 gene expression 16 genetics 16 human cell 16 enzyme activity 14