[Blood-brain barrier and the penetration of cytostatic drugs]

The penetration of 12 commonly used anticancer agents through the blood-brain barrier (BBB) was measured in a rat model using a single-injection tissue-sampling technique. Two of the tested drugs penetrated the barrier, but only to a limited extent. Entry of the drugs into the brain tissue critically depends on molecular weight and lipophilia of the respective test compound. For drugs with a molecular weight of less than 500, BBB simply behaves like an oil/water interphase, whereas drugs with a molecular weight greater than 500 are practically excluded from transport through the BBB even if they show a favourable oil/water partition coefficient. However, permeability of cytostatics was strongly increased if short chain alkylglycerols, up to final concentrations of about 0.3 mol/l were added to the injected solution. Under these conditions the Brain-Uptake-Index (BUI) reached values up to about 50% (cyclophosphamide), depending on lipid solubility and molecular dimension of the respective test compound and the alkyl chain length of the glycerol derivative.