Blood brain barrier

The blood-brain barrier (BBB) consists of specialized astrocyte cells that lie between the epithelial cell of the blood vessel and the interstitial layer. This barrier only allows the permeability of the most lipophilic compounds into the brain. In addition, P-glycoprotein is also present and actively transporting drugs out of the lipid membrane of the BBB.

The permeability of the BBB can be manipulated based on the physiochemical design of the compound. For example there are two CNS depressant barbiturates:


  1. Thiopental

    • Small molecule, highly lipid soluble
    • Rapidly enters brain tissue
    • Induction anaesthesia

  2. Phenobarbital

    • Small molecule, highly lipid soluble
    • Slowly enters brain tissue
    • Chronic treatment of epilepsy