Intrathecal is an adjetive that refers to something that happens inside of the spinal canal. For example, intrathecalimmunoglobulin production means production of this substance in the spinal cord[1]..
As other example, 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. The same drug given orally must enter the blood stream and has a much harder time reaching the brain; by the time it does, most of the drug has been absorbed by the body's system and is excreted. Drugs given intrathecally often have to be made up specially by a pharmacist or technician because they cannot contain any preservative or other potentially harmful inactive ingredients that are sometimes found in standard injectable drug preparations.
Popular for a single 24-hour dose of analgesia (opioid with Local anesthetic)
Caution because of late onset respiratory depression
Severe pruritus and urinary retention may limit the use of intrathecal morphine
Pethidine has the unusual properties of being both a local anaesthetic and opioid analgesic which occasionally permits its use as the sole intrathecal anaesthetic agent.
Intrathecal chemotherapy
Currently, only three agents are licensed for intrathecal chemotherapy
They are methotrexate, cytarabine (a.k.a. Ara-C) and hydrocortisone
Administration of other chemotherapeutic agents with the intrathecal route could lead to fatal outcomes.
Intrathecal Baclofen
Often reserved for spasticcerebral palsy, intrathecally-administered baclofen is done through a intrathecal pump implanted just below the skin of the stomach with a tube connected directly to the base of the spine, where it bathes the appropriate nerves using a dose about one thousand times smaller than that required by orally-administered baclofen. Intrathecal baclofen also carries none of the side effects, such as sleepiness, that typically occur with oral baclofen. It is the preferred route for long-term management of spasticity in people with CP for whom other procedures, such as rhizotomy or orthopedic surgery, are inappropriate.
References
^ Meinl E, Krumbholz M, Derfuss T, Junker A, Hohlfeld R. Compartmentalization of inflammation in the CNS: A major mechanism driving progressive multiple sclerosis, J Neurol Sci. 2008 Aug 18, PMID 18715571
