Why penicillin don pass blood brain barrier?
Meningitis is an infection/inflammation of the meninges – which I suspect you already know since this is a well thought out and difficult question. The disease process itself interferes with the normal functioning of the blood brain barrier. As the infection subsides and inflammatory changes resolve, the integrity of the blood brain barrier returns, and it becomes more difficult for penicillin to cross. Why it does not cross normally is a biochemical phenomenon which has been examined. It’s complicated, but the simple answer is that it is probably related to water solubility of the penicillin molecule. Lipid soluble molecules pass more easily. Below is one site. If you search “penicillin blood brain barrier” you will get much more complex basic science research on this topic. It depends how deep you want to go with this. When I saw this question I first thought that penicillin DOES cross, but you are right – normally it does not cross well. We used various penicillins for decades to tr
