Fluoxetine. Computer model of a molecule of the drug fluoxetine. It is sold under the brand name Prozac. It is a selective serotonin reuptake inhibitor, antidepressant drug, used to treat depression. This drug was developed by Eli Lilly. The molecule's chemical formula is C17.H18.F3.N.O. Atoms (spheres) are colour-coded: carbon (grey), hydrogen (light blue), fluorine (green), nitrogen (dark blue), oxygen (orange).