BAY 73-6691 racemate is primarily utilized in research settings to study its effects on cognitive functions, particularly memory and learning. It acts as a phosphodiesterase 9 (PDE9) inhibitor, which plays a role in regulating cyclic guanosine monophosphate (cGMP) levels in the brain. By inhibiting PDE9, it enhances cGMP signaling, which is associated with improved synaptic plasticity and neuronal communication. This makes it a valuable tool in neuroscience research for exploring potential therapeutic applications in neurodegenerative diseases such as Alzheimer's disease, where cognitive decline is a major concern. Additionally, it is used in preclinical studies to investigate its potential in treating other conditions related to cognitive impairment or memory dysfunction. Its application is largely confined to experimental and developmental stages, with a focus on understanding its mechanisms and efficacy in improving brain function.