An intrathecal injection (often simply called "intrathecal") is an injection into the spinal canal (intrathecal space surrounding the spinal cord), as in a spinal anaesthesia or in chemotherapy or pain management applications. This route is also used for some infections, particularly post-neurosurgical. The drug needs to be given this way to avoid the blood brain barrier. If the drug were given via other routes of administration where it would enter the blood stream it would be unable to reach the brain. Drugs given intrathecally often have to be made up specially by a pharmacist because they cannot contain any preservative or other potentially harmful inactive ingredients that are sometimes found in standard injectable drug preparations.
Intrathecal administration of analgesia:
- Popular for a single 24-hour dose of analgesia (opioid with L/A)
- Caution because of late onset respiratory depression
- Severe pruritus and urinary retention may limit the use of intrathecal morphine