controlled study unclassified drug nonhuman 1,250 article 1,115 priority journal 903 Animals 745 animal cell 533 human 479 Humans 441 Article 380 metabolism 373 animal experiment 359 mouse 350 protein expression 342 human cell 337 Mice 290 animal 288 animal tissue 269 female 255 male 236 enzyme activity 222 Female 208 in vitro study 205 chemistry 197 animal model 193 Male 191 protein function 190 rat 173 genetics 162 Rats 149