HER2 Support Group Forums - View Single Post - for those with (or worried about) brain mets Avastin seems to cross the bbb

Lani · 03-02-2007, 06:31 PM

As I understand it--sometimes the drug crosses the blood brain barrier when it is intact eg. if the size of the molecule is small enough for it to get through. It is not just the size of the molecule of the drug as given, but many drugs circulate bound to proteins, which makes the size the blood brain barrier (which is like a sieve) "sees" just that much bigger.

Yes it seems that sometimes a drug can have an effect outside the Central Nervous System which produces a substance, immune effect or alters some pathway which produces different metabolites which do/does cross the blood brain barrier.

Also, sometimes the disease itself (or the treatment given for it eg radiation) can make the blood brain barrier more permeable (eg. think of making the pores of the seive bigger which lets more in)

So I would think there are many ways to outwit the Blood brain barrier. As we discover more about it, hopefully more will be found.

By the way, the rate of autopsy is AMAZINGLY low. People don't agree to it as often, doctors don't ask for it as often and institutions are not willing to "ruin their bottom line" by performing the studies needed to learn from those who have died--as it is not reimbursed by insurance companies.

03-02-2007, 06:31 PM	#4
Lani Senior Member Join Date: Mar 2006 Posts: 4,778	Alaska Angel As I understand it--sometimes the drug crosses the blood brain barrier when it is intact eg. if the size of the molecule is small enough for it to get through. It is not just the size of the molecule of the drug as given, but many drugs circulate bound to proteins, which makes the size the blood brain barrier (which is like a sieve) "sees" just that much bigger. Yes it seems that sometimes a drug can have an effect outside the Central Nervous System which produces a substance, immune effect or alters some pathway which produces different metabolites which do/does cross the blood brain barrier. Also, sometimes the disease itself (or the treatment given for it eg radiation) can make the blood brain barrier more permeable (eg. think of making the pores of the seive bigger which lets more in) So I would think there are many ways to outwit the Blood brain barrier. As we discover more about it, hopefully more will be found. By the way, the rate of autopsy is AMAZINGLY low. People don't agree to it as often, doctors don't ask for it as often and institutions are not willing to "ruin their bottom line" by performing the studies needed to learn from those who have died--as it is not reimbursed by insurance companies.