Intrathecal
Intrathecal is an adjective that refers to something introduced into or occurring in the space under the arachnoid membrane of the brain or spinal cord.[1] For example, intrathecal immunoglobulin production means production of this substance in the spinal cord.[2]
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.
Intrathecal administration of analgesia
- Very 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
- Administration of other chemotherapeutic agents such as vincristine via the intrathecal route can lead to fatal outcomes.[3][4]
Intrathecal baclofen
Often reserved for spastic cerebral palsy, intrathecally-administered baclofen is done through an 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. However, intrathecal baclofen pumps carry serious clinical risks, such as infection or a possibly fatal sudden malfunction, that oral baclofen does not.
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See also