Why adrenaline don´t cross the BBB?

[Balan]

Hello guys, I can´t find the explanation for this question, why adrenaline don´t cross the blood-brain barrier.
I think about the MAO inhibitors interaction, reasoning with the treatment of Parkinson´s Disease when L-Dopa neeed to be administred with Carbidopa to allow the L-Dopa be converted in Dopamine, but I am not sure about that, because I know the Dopamine can´t corss because this will be degraded.

Well if someone can help me about this I appreciate.

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[Hoya2009]

I don't understand most of what you wrote, but there is significant dopamine decarboxylase in the periphery. Those are the target of carbidopa.
I don't know where MAO and epi fit into this picture. Epi doesn't cross because its polar and isn't actively transported, the same reason everything that doesn't cross the BBB.

 

[Balan]

Thank you.

 

[HelpPleaseMD]

1) Dopamine does not cross the BBB.
2) Parkinson's disease is characterized by an imbalance between acetylcholine and dopamine (D2). There is too much acetylcholine and too little of dopamine so the strategy in treating Parkinson's disease is to try and restore the balance between the two.

To decrease acetylcholine any antimuscarinic drug that crosses the CNS can be used. Classically they are the dimenhydramines and the benzotropines. These drugs improve the negative symptoms of parkinson's disease such as bradykinesia but not the symptoms relating to starting motion.

The dopamine agonist drugs come in several flavors. There are a lot so im not going to type them all out. Basically you can directly administer dopamine agonist via pergolide or bromocriptine but these arent used often...... and so on. sorry got tired typing lol. But looking at the FA pharm section there are some drugs that may be missing like entacopone (COMT inhibitor)

 

[HelpPleaseMD]

If you google the structures of dopamine and noreepi/epi you will see that the structures are polar. Polar molecules do not diffuse across the Blood brain barrier.