If you search Metanx here you'll find posts on PN about it.

It is a medical food, and not a drug and does not have DRUG FDA approval. Medical foods are a separate category at the FDA.

It has high dose methylfolate, activated B6, and methylcobalamin in it. You should take it on empty stomach if you want the benefits of the B12. That is all it is.

Here is the insert:
http://www.metanx.com/helpful-resources/package-insert/

The antibiotic statement is near the end. I have not heard of this statement before.
I'll have to search this quote. B12 is excreted in the bile, and some may be reabsorbed in the intestine, but that has always been unclear in most of what I have read...not proven therefore.

It is always best to take methylB12 on an empty stomach...for best absorption.

Thank you Mrs D for your comments/insights, as usual. I am excited because its something new. At least something new is prescribed to me. Anything that is new gives me hope for improvement.
I am in a dilemma, though, to start because of the vit b12 component. I have bloodworks in May that include vitB12, I want to get my real numbers without supplementation.

Btw, I am taking vit d3 because Rifampin, one of my antibiotics affect the absorption of vit d3 and you know what my number last march 7---it's 66.5 (Vit D, 25-hydroxy). I'm taking 4000mg+. I'm happy that its a good number, unfortunately it does not help my pain. I still take it for my lungs.

Thank you for all your help.

That is great about your Vit D.

The reason Metanx is RX is that it has 1mg or more of folate in it.
That is the only reason. FDA requires an RX for 1mg or more of folic acid or folate.

It is up to you to decide when to start it. It should be taken on an empty stomach for best absorption.

You haven't been on B12 at all before?

I have been on Vit B12 methylcobalamin a few months after my PN started. Got it from you. The last b12 test I had was August 2012 and my result was 1999. Since then I take my vitb12 twice a week to comply the 5000mcg (mine at home is 2500mcg). I will have my b12 test in May so I want to stop it so I can see my real number without supplementation. I remember, though, in one of your posts that only 3 days is required to flush out all b12 in the system. I hope I remember your post right. :-)