Can anyone here help me out with specifics about how and where Methyldopa works? I have POTS with blood pooling and hyperandrenergic components (and NMS). I also have ADHD. I take Strattera for that, and it is a NE retake inhibitor. Works very well for my ADHD, especially in combination with fish oil. My tilt table test was done Strattera-free for 1 day. Yes, it takes 3-4 days to completely clear from the body of a normal metabolizer, but cardiologist knows this and said 1 day was enough. Plasma NE was 1962 standing, not measured supine. Cardiologist and neurologist both insist that the brain can be deficient in NE (and hence ADHD) and my body concurrently be producing too much. They also both believe that the Strattera is not causing POTS. Atenolol made me depressed, so cardiologist suggested Methyldopa as having lower potential to cause problems than Clonidine. So far it seems to be helping a little (not getting so tired as quickly), but I've only been on it for a few days. Now the question: Does the Methyldopa work in the brain or in the body? If in the brain, will it cancel out the Strattera and make my ADHD worse? Why or why not? So far it doesn't seem to be doing that, but if it is a false neurotransmitter, maybe it needs time to build up to full action? I would like to understand better, but I'm not sure where to go to learn more without taking on a full class about the nervous system. I need to spend my time preparing my own classes to teach instead (sedimentology)! Can anyone help me out here?