What are the strategies used to deliver the drugs to the cns?

Many. Drugs may reach the CNS through several ways, depending upon the particular drug chemistry and the integrity of the blood brain barrier. Methods of CNS drug administration include: oral, intravenous, intrathecal (to the spinal fluid), convection enhanced delivery (directly to the brain through a catheter) and surgical implantation of drug wafers. This is a complex subject.