Ciclosporin !

A transplant medicine that keeps T cells from attacking the new organ. Its blood level is measured, and it can raise blood pressure and harm the kidneys.

Updated 2026-11-01

Class: Calcineurin inhibitors
Enzyme: Calcineurin, through cyclophilin A
ATC code: L04AD01
WHO Model List of Essential Medicines

Also called: cyclosporine, cyclosporin A

Calcineurin, through cyclophilin ACiclosporin

The figure shows the human complex of calcineurin, cyclophilin A and ciclosporin. Ciclosporin is a cyclic peptide, so in this entry it is a peptide chain rather than a small-molecule ligand.

Target in 3D: Calcineurin, through cyclophilin A. PDB structure 1MF8 (RCSB PDB, public domain). View the structure at RCSB PDB

Mechanism of action

Ciclosporin is a cyclic peptide of fungal origin. Inside T cells it binds cyclophilin, and the complex inhibits calcineurin. NFAT is not dephosphorylated and cannot reach the nucleus, so IL-2 and other cytokines are not produced and T-cell activation and proliferation are blocked.

Binds cyclophilin inside the T cell
The complex blocks the phosphatase calcineurin
NFAT stays in the cytoplasm: no IL-2 is made
T cells do not proliferate against the graft

Pharmacokinetics

Absorption: Oral absorption is variable; different oral formulations are not bioequivalent
Metabolism: Extensively in the liver and gut by CYP3A4; also a P-glycoprotein substrate
Elimination: Mainly in the bile, as metabolites
Half-life: About 8 hours on average, ranging widely between patients

Indications

Prevention of rejection of kidney, liver and heart transplants
Severe active rheumatoid arthritis that has not responded to methotrexate Rheumatoid arthritis →
Severe plaque psoriasis that has not responded to other systemic treatment
Crohn disease, off label in some cases Crohn disease →

Adverse effects

Common

Hypertension
Tremor
Hirsutism
Gum hyperplasia
Hyperkalaemia and low magnesium
Raised lipids and uric acid

Contraindications

Hypersensitivity to ciclosporin or the formulation
In rheumatoid arthritis or psoriasis: abnormal kidney function, uncontrolled hypertension or malignancy
In psoriasis: concurrent PUVA or UVB therapy, methotrexate or other immunosuppressants

Key interactions

CYP3A4 inhibitors (azole antifungals, macrolides, diltiazem, verapamil) and grapefruit: Raise ciclosporin levels and toxicity.
CYP3A4 inducers (rifampicin, carbamazepine, phenytoin, St John's wort): Lower ciclosporin levels: risk of rejection.
Statins: Ciclosporin raises statin levels: myopathy and rhabdomyolysis.
Potassium-sparing diuretics: Hyperkalaemia; not used together.
Other nephrotoxic drugs (aminoglycosides, NSAIDs): Additive kidney damage.

What is monitored

Ciclosporin trough blood levels
Creatinine and urea
Blood pressure
Potassium, magnesium, uric acid and lipids
Skin checks for cancer

Administration and safety

Oral capsules or solution and an intravenous form; different oral formulations are not bioequivalent and are not swapped without specialist supervision.
The oral solution is diluted, preferably with orange or apple juice at room temperature, as the label describes.
Taken on a consistent schedule, at the same times of day and in the same relation to meals.

Nursing care

Take blood for trough levels before the dose, as scheduled.
Measure blood pressure at every visit.
Check creatinine, potassium and magnesium results.
Teach to avoid grapefruit and to report all new medicines and herbal products.
Teach sun protection and the signs of infection; avoid live vaccines.

Pregnancy and breastfeeding

Used in pregnancy after transplantation when needed; the treating team weighs the risk of rejection against the risks to the fetus.

Test yourself

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

Which adverse effects help tell ciclosporin from tacrolimus?

Gum hyperplasia and hirsutism are typical of ciclosporin; tacrolimus causes more new-onset diabetes and neurotoxicity. Both are nephrotoxic.

Why are trough levels of ciclosporin measured?

Its absorption and metabolism vary a lot, and both low levels (rejection) and high levels (nephrotoxicity) are dangerous.

Why should a patient on ciclosporin avoid potassium-sparing diuretics?

Ciclosporin itself can cause hyperkalaemia; adding a potassium-sparing diuretic increases that risk.

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

Sources: Cyclosporine: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2023); DailyMed - CYCLOSPORINE solution (DailyMed (U.S. National Library of Medicine), 2025); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 39 (McGraw Hill, 2023).

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Representative model, for educational purposes only.