Expert: Dr.Paul Skett - 8/7/2002

Question
Hi
Can you tell me why CNS drugs like amphetamine can cross the BBB of brain,some drugs cannot?


Answer
Hi, Sinn,

BBB is just that the cells lining the capillaries in the brain are pushed tightly together (unlike eldewhere in the body where there are gaps for the drugs to get through).

So drug needs to cross the cell lining the capillary to get into the brain. Cell membranes are made of fat (lipid) and, thus, drug needs to be able to dissolve in fat to get through. Amphetamines are fat soluble whereas some other drugs are not - thus, they get in while others don't.

Hope this helps.

Best wishes,

Paul