Chemo administered to treat CNS disease is delivered via which route?

• A. Intravesicular
• B. Intrathecal
• C. Intra-arterial
• D. Intraperitoneal

Answer: (B)

When treating CNS disease with chemotherapy, the drug must reach the cerebrospinal fluid to affect the brain and spinal cord, because the blood-brain barrier blocks many systemic chemotherapies. Delivering the drug directly into the CSF allows distribution throughout the CNS with higher local concentrations and often lower systemic toxicity. This direct CSF administration is intrathecal delivery, typically via lumbar puncture or an implanted reservoir. Other routes don’t target the CSF: intravesical goes to the bladder, intraperitoneal to the peritoneal cavity, and intra-arterial aims at arteries supplying the brain but is not the standard approach for CNS-wide disease.