IGF-1 LR3

An engineered IGF-1 variant made to dodge its binding proteins; built as a cell-culture reagent and never tested in a published human trial.

Also known as: Long R3 IGF-1, LR3-IGF-I, Long Arg3 IGF-I
Area: Hormones
Status: Never approved or clinically tested; a laboratory reagent, banned in sport

Articles on IGF-1 LR3

HormonesPreclinical

IGF-1 LR3: a laboratory reagent with no published human studies

IGF-1 LR3 was built in 1992 to make cells grow faster in culture. Nobody has published a trial of it in people, and the approved version of IGF-1 carries a low blood sugar warning.

HPR Editorial · 12 Sept 2026 · 7 min read