chemistry

Tacrolimus

Tacrolimus is a chemistry 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 Tacrolimus rather than just read about it. In short: Tacrolimus, sold under the brand name Prograf among others, is an immunosuppressive drug. After an allogenic organ transplant, the risk of organ rejection is moderate; tacrolimus is used to lower the risk of organ rejection.

Key takeaways

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

Reference excerpt

Tacrolimus, sold under the brand name Prograf among others, is an immunosuppressive drug. After an allogenic organ transplant, the risk of organ rejection is moderate; tacrolimus is used to lower the risk of organ rejection. Tacrolimus is also sold as a topical medication for treating T cell-mediated diseases, such as eczema and psoriasis. For example, it is prescribed for severe refractory uveitis after a bone marrow transplant, exacerbations of minimal change disease, Kimura's disease, and vitiligo. It can be used to treat dry eye syndrome in cats and dogs. Tacrolimus inhibits calcineurin, which is involved in the production of interleukin-2, a molecule that promotes the development and proliferation of T cells, as part of the body's learned (or adaptive) immune response. Chemically, it is a macrolide lactone that was first discovered in 1987, from the fermentation broth of a Japanese soil sample that contained the bacterium Streptomyces tsukubensis. It is on the World Health Organization's List of Essential Medicines. In 2021, it was the 296th most commonly prescribed medication in the United States, with more than 500,000 prescriptions.

History Tacrolimus was discovered in 1987 by a Japanese team led by pharmacologist Tohru Kino; it was among the first macrolide immunosuppressants discovered, preceded by the discovery of rapamycin (sirolimus) on Rapa Nui (Easter Island) in 1975. It is produced by a soil bacterium, Streptomyces tsukubensis. The name tacrolimus is derived from "Tsukuba macrolide immunosuppressant". The early development (investigational new drug phase) of tacrolimus, called at the time by the development code FK-506, happened in the next several years. A firsthand account of that process is given in Thomas Starzl's 1992 memoir. Tacrolimus was first approved by the US Food and Drug Administration (FDA) in 1994, for use in liver transplantation; the indications were extended to include kidney transplants. The first generic version of tacrolimus (capsule for oral route) was approved in the US in 2009. A generic version of tacrolimus for injection was approved in the US in 2017. Tacrolimus was approved for medical use in the European Union in 2002, for the treatment of moderate to severe atopic dermatitis. In 2007, the indications were expanded to include the prophylaxis of transplant rejection in adult kidney or liver allograft recipients and the treatment of allograft rejection resistant to treatment with other immunosuppressive medicinal products in adults. In 2009, the indications were expanded to include the prophylaxis of transplant rejection in adult and paediatric, kidney, liver or heart allograft recipients and the treatment of allograft rejection resistant to treatment with other immunosuppressive medicinal products in adults and children.

Medical uses

Organ transplantation It has similar immunosuppressive properties to ciclosporin, but is much more potent. Immunosuppression with tacrolimus was associated with a significantly lower rate of acute rejection compared with ciclosporin-based immunosuppression (30.7% vs 46.4%) in one study. Clinical outcome is better with tacrolimus than with ciclosporin during the first year of liver transplantation. Long-term outcome has not been improved to the same extent. Tacrolimus is normally prescribed as part of a post-transplant cocktail including steroids, mycophenolate, and IL-2 receptor inhibitors such as basiliximab. Dosages are titrated to target blood levels at specific times after medication administration.

Skin

As an ointment, tacrolimus is used in the treatment of dermatitis (eczema), in particular atopic dermatitis, if topical corticosteroids and moisturisers fail in helping. It suppresses inflammation in a similar way to steroids, and is equally as effective as a mid-potency steroid. An important advantage of tacrolimus is that, unlike steroids, it does not cause skin thinning (atrophy), or other steroid related side effects. It is applied on the active lesions until they heal off, but may also be used continuously in low doses (twice a week), and applied to the thinner skin over the face and eyelids. Clinical trials of up to one year have been conducted. Recently it has also been used to treat segmental vitiligo in children, especially in areas on the face.

Eyes Tacrolimus solution, as drops, is sometimes prescribed by veterinarians for keratoconjunctivitis, and other dry eye maladies, in the eyes of domestic cats, dogs, and horses. It has been studied for use in human eyes.

Contraindications and precautions Contraindications and precautions include:

Hepatic disease Immunosuppression Infants Infection Neoplastic disease, such as: Skin cancer Lung cancer Oliguria Pregnancy QT interval prolongation Sunlight (UV) exposure Grapefruit juice

Topical use Occlusive dressing Known or suspected malignant lesions Netherton's syndrome or similar skin diseases Certain skin infections

Side effects

By mouth or intravenous use Side effects can be severe and include infection, cardiac damage, hypertension, blurred vision, liver and kidney problems (tacrolimus nephrotoxicity), hyperkalemia, hypomagnesemia, hyperglycemia, diabetes mellitus, itching, lung damage (sirolimus also causes lung damage), and various neuropsychiatric problems such as loss of appetite, insomnia, posterior reversible encephalopathy syndrome, confusion, weakness, depression, vivid nightmares, cramps, neuropathy, seizures, tremors, and catatonia. In addition, it may potentially increase the severity of existing fungal or infectious conditions such as herpes zoster or polyoma viral infections.

Carcinogenesis and mutagenesis In people receiving immunosuppressants to reduce transplant graft rejection, an increased risk of malignancy (cancer) is a recognised complication. The most common cancers are non-Hodgkin's lymphoma and skin cancers. The risk appears to be related to the intensity and duration of treatment.

Topical use The most common adverse events associated with the use of topical tacrolimus ointments, especially if used over a wide area, include a burning or itching sensation on the initial applications, with increased sensitivity to sunlight and heat on the affected areas. Less common are flu-like symptoms, headache, cough, and burning eyes.

Cancer risks

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Tacrolimus

Start with the simplest possible case. Write down what Tacrolimus claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, 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 Tacrolimus 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 Tacrolimus 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 Tacrolimus

In research: Tacrolimus appears in chemistry 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 Tacrolimus 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: Tacrolimus is common in secondary-school and first-year university syllabi. It links to neighbouring topics Alkene derivatives, Allyl compounds, Astellas Pharma, so understanding it makes those chapters shorter.
In everyday life: Look for Tacrolimus 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 Tacrolimus in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Tacrolimus 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 Tacrolimus out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Tacrolimus in simple terms?

Why does Tacrolimus matter?

Because it connects several chemistry 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 Tacrolimus?

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 Tacrolimus.