Liraglutide Crosses Blood-Brain Barrier, Detected in Spinal Fluid

The GLP-1 receptor agonist liraglutide is widely used for treating Type 2 diabetes and obesity, primarily acting on peripheral tissues. However, its potential direct effects on the central nervous system (CNS), which could influence appetite, metabolism, and even neuroprotection, depend on its ability to cross the blood-brain barrier (BBB), a protective layer of cells that controls what substances can enter the brain from the bloodstream. This study specifically aimed to determine whether liraglutide can transfer from the blood into the cerebrospinal fluid (CSF), the fluid surrounding the brain and spinal cord.

The study successfully demonstrated that liraglutide can indeed cross the blood-brain barrier (BBB) and be detected in the cerebrospinal fluid (CSF). Specifically, liraglutide was found in the CSF of 7 out of 8 patients (87.5% of participants). The median CSF concentration of liraglutide was 0.0004 nmol/L (with a range from 0 to 0.0012 nmol/L) at 60 minutes post-injection. This resulted in an extremely low median CSF/plasma ratio of 0.00007 (ranging from 0 to 0.0002), indicating a very limited but consistent transfer. The study found that liraglutide was detectable in the cerebrospinal fluid of 7 out of 8 patients with Type 2 diabetes, demonstrating its ability to cross the blood-brain barrier, albeit at very low concentrations.