Droxidopa (Northera) is an approved drug for the treatment of low blood pressure in PD. It is a norepinephrine precursor, which is converted in the body to the neurotransmitter norepinephrine. This is a chemical that the body normally makes that has a variety of important activities in the brain and peripheral nervous system. In PD, the cells that make norepinephrine die off as part of the disease process. Therefore, people with PD often have low levels of norepinephrine in their blood and in their spinal fluid. Norepinephrine is important for maintaining blood pressure, which may be one reason that some people with PD have problems with their blood pressure falling too low when they stand up. This can lead to symptoms such as dizziness, lightheadedness, feeling faint, or sometimes passing out.