intravenous drug administration animal experiment 40 article 28 nonhuman 24 Animal 22 rat 22 Male 20 Rats 20 priority journal 20 Female 18 human 18 drug efficacy 16 Support, Non-U.S. Gov't 14 endocrine system 14 drug mechanism 12 male 12 therapy 12 Animalia 10 Diabetes Mellitus, Experimental 10 animal cell 10 oral drug administration 10 subcutaneous drug administration 10 Animals 8 Insulin 8 animal 8 cardiovascular system 8 central nervous system 8 dog 8 dose response 8 female genital system 8