science

Intrathecal administration

Intrathecal administration is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Intrathecal administration rather than just read about it. In short: Intrathecal administration is a route of administration for drugs via an injection into the spinal canal, or into the subarachnoid space (syn. intrathecal space) so that it reaches the cerebrospinal fluid (CSF). It is useful in several applications, such as for spinal anesthesia, chemotherapy, or pain management.

Key takeaways

Intrathecal administration belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Intrathecal administration to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Intrathecal administration from memory before moving on to harder problems.

Reference excerpt

Intrathecal administration is a route of administration for drugs via an injection into the spinal canal, or into the subarachnoid space (syn. intrathecal space) so that it reaches the cerebrospinal fluid (CSF). It is useful in several applications, such as for spinal anesthesia, chemotherapy, or pain management. This route is also used to introduce drugs that fight certain infections, particularly post-neurosurgical. Typically, the drug is given this way to avoid being stopped by the blood–brain barrier, as it may not be able to pass into the brain when given orally. Drugs given by the intrathecal route often have to be compounded 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 pseudodelivery is a particular method of intrathecal administration, whereby the drug is encapsulated in a porous capsule that is placed in communication with the CSF. In this method, the drug is not released into the CSF. Instead, the CSF is in communication with the capsule through its porous walls, allowing the drug to interact with its target within the capsule itself. This allows for localized treatment while avoiding systemic distribution of the drug, potentially reducing side effects and enhancing the therapeutic efficacy for conditions affecting the central nervous system. The route of administration is sometimes simply referred to as "intrathecal"; however, the term is also an adjective that refers to something occurring in or introduced into the anatomic space or potential space inside a sheath, most commonly the arachnoid membrane of the brain or spinal cord (under which is the subarachnoid space). For example, intrathecal immunoglobulin production is production of antibodies in the spinal cord. The abbreviation "IT" is best not used; instead, "intrathecal" is spelled out to avoid medical mistakes.

Applications of intrathecal administration

Pain treatment

Anaesthetics/analgesics Intrathecal administration of drugs for anaesthesia or analgesia can be utilized in the form of single-dose or continuous via catheter with external or internal pump depending on indication and duration needed. Usually a combination of a local anesthetic and one or more adjuvant drugs are used.

Alpha-adrenergic agonists Intrathecal clonidine or dexmedetomidine can be used to prolong duration of anaesthesia and analgesia but comes with increased risk of hypotension.

Opioids Lipophilic opioids such as fentanyl and sufentanil can be administered intrathecally for short duration of anaesthesia and analgesia. Hydrophilic opioids such as morphine, diamorphine and hydromorphone can be administered intrathecally for longer duration of analgesia, up to 24 hours. Pethidine has the unusual property of being both a local anaesthetic and opioid analgesic, which occasionally permits its use as the sole intrathecal anaesthetic agent. Caution should be exercised with intrathecal opioids due to the risk of hypoventilation. Hydrophilic opioids come with a dose-dependent risk of late onset hypoventilation, however, low-dose intrathecal hydrophilic opioids have similar risk for hypoventilation as systemic opioids. Other adverse effects of intrathecal opioids include nausea and vomiting, pruritus and urinary retention.

Atypical analgesic agents Ziconotide.

Antifungals Amphotericin B is administered intrathecally to treat fungal infections involving the central nervous system infections.

Cancer chemotherapy Currently, only four agents are licensed for intrathecal cancer chemotherapy: methotrexate, cytarabine, hydrocortisone, and thiotepa. Administration of any vinca alkaloids, especially vincristine, via the intrathecal route is nearly always fatal.

Baclofen Often reserved for spastic cerebral palsy, baclofen can be administered through an intrathecal pump implanted just below the skin of the abdomen or behind the chest wall, with a catheter connected directly to the base of the spine. Intrathecal baclofen pumps sometimes carry serious clinical risks, such as infection or a possibly fatal sudden malfunction.

Antisense therapy Intrathecal administration of antisense oligonucleotides. Neurodegenerative diseases that are a result of a single mutant protein are good targets for antisense oligonucleotide therapies because of their ability to target and modify very specific sequences of RNA with high selectivity. Treatment of spinal muscular atrophy with Nusinersen is an example.

Mesenchymal Stem Cell Therapy Treatment of chronic spinal injuries via the administration of mesenchymal stem cells, either from adipose tissue or bone marrow, is experimental, with better results from the former method. Introduction of mesenchymal stem cells promote the microenvironment needed for axonal regrowth and reduction of inflammation caused by astrocytes proliferation and glial scar tissue. Animal models have shown improved motor control under the site of injury. A clinical trial also showed statistically significant improved sensitivity under the site of injury in patients.

See also Cancer pain/Interventional/Intrathecal pump History of neuraxial anesthesia Intrathecal pump Theca Thecal sac Lumbar puncture

References

Illustrations

Worked examples

Example 1 — a first encounter with Intrathecal administration

Start with the simplest possible case. Write down what Intrathecal administration claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Intrathecal administration before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Intrathecal administration ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Intrathecal administration

In research: Intrathecal administration appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Intrathecal administration in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Intrathecal administration is common in secondary-school and first-year university syllabi. It links to neighbouring topics Dosage forms, Medical treatments, Routes of administration, so understanding it makes those chapters shorter.
In everyday life: Look for Intrathecal administration outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Intrathecal administration in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Intrathecal administration means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Intrathecal administration out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Intrathecal administration in simple terms?

Why does Intrathecal administration matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Intrathecal administration?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Intrathecal administration.