Posted by Ron Hill on March 19, 2008, at 23:39:29
In reply to Re: Nardil plus Phenylethylamine (PEA), posted by undopaminergic on March 19, 2008, at 14:51:37
undopaminergic,
Thank you for your post. I respect your knowledge of neurochemistry.
> PEA is considerably more risky than phenylalanine (PA), because it can rapidly release noradrenaline from storage vesicles in sympathetic nerve terminals, whereas PA first has to be converted into an active compound.
At what dosage level does PEA release NE from storage vesicles in sympathetic nerve terminals? Can you point me to a research document discussing this issue? I've not seen this stated anywhere in the literature. Thanks for your help.
> DA is more hypotensive than hypertensive (except perhaps at very high concentrations), so any risk it may present is likely to be through its conversion into noradrenaline.
Exactly, NE is the issue.> More importantly, it should be emphasised that the conversions of phenylalanine to tyrosine and tyrosine to L-dopa are relatively slow processes. L-dopa synthesis is the rate-limiting step in the production of catecholamines. Additionally, excessive concentrations of PA can further slow down the synthesis of L-dopa due to competitive inhibition of tyrosine hydroxylase (TH).
Thanks for the information. But, why then, on page 2 of the Nardil Prescribing Information (Pfizer) document, is PA specifically contraindicated for the same reasons I put forth in my original post?
http://www.pfizer.com/files/products/uspi_nardil.pdf
On the other hand, PEA has been used safely with Nardil in small open trials. PEA must be treated with care and respect, but it can be done.
Others can do what they deem appropriate. But, for me, I'll follow Pfizer's warning and use PEA directly, yet carefully.
> Catecholamines are also metabolised by catechol-O-methyltransferase (COMT), so they can be broken down even without MAO, albeit at a reduced rate.Clearly, catecholamines are not metabolized fast enough by COMT to avoid a hypertensive crisis in all situations.
Thanks again for your thought provoking post.
-- Ron
poster:Ron Hill
thread:818442
URL: http://www.dr-bob.org/babble/20080316/msgs/818950.html