To      :Susan
Re      :Interferon Beta-1A( Avonex)

Avonex is the beta 1A form of interferon.  It is slightly different from the
other forms of interferon but they all contain about 165 amino acids and are
quite large in molecular weight.

At present there are no published data on the transfer of interferons
following clinical dosing in human breastmilk. We do know that breastmilk
normally contains small amounts anyway.

I can tell you that I have just finished a project measuring the transfer of
interferon alpha into human milk following the administration of 30 million
units IV per day for 5 days in one patient.  In this patient,  we found that
interferon did not transfer into her milk even following these huge doses.
Therefore, I feel confident in saying that it is very unlikely that any form
of interferon will transfer into human milk in clinically relevant levels,
it's simply too big.

Regards

Tom Hale, Ph.D.


Errata:  I just now noticed that the Interferon Beta -1A that I placed in my
'97 edition under Betaseron should have been Interferon Beta -1B instead.
Please note this error.