system
Given the following post, respond as if you're commenting on Reddit:
human
Why are re-uptake inhibitors used instead of the neurotransmitters themselves?

You go to the doctor depressed and they say you have low serotonin levels that's why your depressed. So why not just give the person serotonin instead of a drug that just makes your brain not recycle it so quickly?
gpt
Multiple reasons:

* They want drugs with long half lives so that you're not taking it every half hour. Serotonin would be rapidly processed. Reuptake inhibitors get stuck in molecular channels and hang out longer.


* Your brain has a blood brain barrier to filter out possibly dangerous molecules, viruses, bacteria, etc. Serotonin does not get through the blood brain barrier, so any you took would not make it to your brain.