[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › Calcineurin inhibitors

[Pharmacology](https://durgical.com/en/pharmacology/) · Class

# Calcineurin inhibitors

Transplant medicines that stop T cells from switching on by blocking calcineurin. Their blood levels are measured, and they can harm the kidneys.

Updated 2026-11-01

## What they are

The backbone of maintenance immunosuppression after kidney, liver and heart transplantation: ciclosporin and tacrolimus. Ciclosporin is also used for severe psoriasis and rheumatoid arthritis; both are used off label in some inflammatory bowel disease.

## Mechanism of action

Each drug first binds an immunophilin inside the T cell: ciclosporin binds cyclophilin, tacrolimus binds FKBP12. The drug-immunophilin complex blocks calcineurin, a calcium-dependent phosphatase. Without calcineurin, the transcription factor NFAT stays phosphorylated in the cytoplasm, the IL-2 gene is not switched on, and T cells do not proliferate in response to the graft.

Target: Calcineurin (protein phosphatase 2B), reached through cyclophilin or FKBP12

## Key points

- Nephrotoxicity is the main dose-related toxicity of both; hypertension, hyperkalaemia and tremor are common.
- Both are CYP3A4 and P-glycoprotein substrates: azole antifungals, macrolides and grapefruit raise levels; rifampicin and anticonvulsants lower them.
- Ciclosporin: gum hyperplasia and hirsutism. Tacrolimus: more new-onset diabetes after transplant and neurotoxicity.
- Trough blood levels are monitored because the window between rejection and toxicity is narrow.
- Higher risk of infections and of skin cancer and lymphoma; live vaccines are avoided.

## Drugs in this class

- [**Ciclosporin** A transplant medicine that keeps T cells from attacking the new organ. Its blood level is measured, and it can raise… Calcineurin, through cyclophilin A](https://durgical.com/en/pharmacology/ciclosporin/)
- [**Tacrolimus** The most used anti-rejection drug after transplants. It blocks T-cell activation; its level is measured, and it can… Calcineurin, through FKBP12](https://durgical.com/en/pharmacology/tacrolimus/)

## Others in the class

- voclosporina

## Test yourself

Think of the answer, then tap the question to see it.

## Which protein does each calcineurin inhibitor bind before it can block calcineurin?

Ciclosporin binds cyclophilin and tacrolimus binds FKBP12; the drug-immunophilin complex is what inhibits calcineurin.

## How does blocking calcineurin stop T-cell activation?

Calcineurin dephosphorylates NFAT so it can enter the nucleus; without it NFAT stays in the cytoplasm and IL-2 and other cytokine genes are not transcribed.

## A transplant patient on tacrolimus starts clarithromycin. What can happen?

Clarithromycin inhibits CYP3A4, so tacrolimus levels rise, with risk of nephrotoxicity, neurotoxicity and hyperkalaemia; levels are checked closely.

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/pharmacology/classes/calcineurin-inhibitors/)

[← All of pharmacology](https://durgical.com/en/pharmacology/)

Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: [DailyMed - TACROLIMUS capsule](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=54fcc518-21d9-44a8-9e2c-87ebc2b3e2e6) (DailyMed (U.S. National Library of Medicine), 2025); [DailyMed - CYCLOSPORINE solution](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=f3dc2a50-1084-4190-a6f3-37034a04db86) (DailyMed (U.S. National Library of Medicine), 2025); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 39 (McGraw Hill, 2023).

## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake

Representative model, for educational purposes only.

---
Source: https://durgical.com/en/pharmacology/classes/calcineurin-inhibitors/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/classes/calcineurin-inhibitors/