Prozac antidepressant drug, molecular model. Prozac is the brand name for the drug fluoxetine. It belongs to a class of drugs called selective serotonin reuptake inhibitors, which work by preventing the reuptake of the neurotransmitter serotonin in the brain. As depression is caused at least in part by low serotonin levels, blocking reuptake can raise the mood and increase energy levels. Prozac is also prescribed for bipolar disorder (manic depression) and obsessive- compulsive disorder. There have been several public health concerns about the drug, but it is still a popular medication. In this molecule, carbon atoms are green, oxygen is pink, nitrogen blue, fluorine orange and hydrogen white.