[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [Kinase inhibitors (targeted oncology)](https://durgical.com/en/pharmacology/classes/kinase-inhibitors/) › Imatinib

# Imatinib

## Kinase inhibitors (targeted oncology)?

Kinase inhibitors (targeted oncology)

## High alert?

An error with this medicine can cause serious harm: double checks and protocols are used.

The first targeted kinase inhibitor: it shuts down BCR-ABL in Philadelphia-positive CML and KIT in GIST. Typical effects: oedema, cramps, nausea.

Updated Nov 1, 2026

Also called: imatinib mesylate, STI571

## Quick facts

**Group**
[Kinase inhibitors (targeted oncology)](https://durgical.com/en/pharmacology/classes/kinase-inhibitors/)

**Target**
BCR-ABL tyrosine kinase (ABL1 kinase domain)

**Used for**
KIT · Hypereosinophilic syndrome

**Key effects**
Oedema · Nausea · Rash

**Monitor**
Complete blood count · Liver function before starting

**ATC**
L01EA01

No doses: the clinician sets them by the current guideline.

On this page

- The basics Mechanism of action
- Indications
- Adverse effects
- Pharmacokinetics
- Memory aid

- Clinical What the labels mean

- Safety Contraindications
- Key interactions
- What is monitored
- Administration and safety
- Pregnancy and breastfeeding
- Nursing care

- Study Test yourself

- Connections Connections

## Mechanism of action

✂**BCR-ABL tyrosine kinase (ABL1 kinase domain)**Imatinib

ⓘ The figure shows imatinib in the ATP pocket of the mouse c-Abl kinase domain, whose site matches the human enzyme; it holds the kinase in its inactive shape.

**Target in 3D:** BCR-ABL tyrosine kinase (ABL1 kinase domain). PDB structure 1IEP (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/1IEP) · Drag to rotate · pinch to zoom

The Philadelphia chromosome, t(9;22), fuses BCR to ABL and creates BCR-ABL, a tyrosine kinase that is always switched on and drives chronic myeloid leukaemia. Imatinib occupies the ATP-binding pocket and locks the kinase in its inactive conformation, so it cannot phosphorylate its substrates; the leukaemic cells stop proliferating and undergo apoptosis. It also inhibits the receptor kinases KIT and PDGFR, which explains its activity in GIST and some eosinophilic disorders.

- t(9;22) creates the always-active BCR-ABL kinase
- Imatinib fills the ATP pocket, inactive shape locked
- No substrate phosphorylation: proliferation stops
- Also blocks KIT and PDGFR (GIST)

## Indications

- Philadelphia chromosome-positive chronic myeloid leukaemia, in adults and children. [Chronic myeloid leukaemia →](https://durgical.com/en/conditions/chronic-myeloid-leukaemia/)
- Philadelphia-positive acute lymphoblastic leukaemia. [Acute leukaemia (AML and ALL) →](https://durgical.com/en/conditions/acute-leukaemia/)
- KIT (CD117)-positive gastrointestinal stromal tumour, advanced or after resection. [Gastrointestinal stromal tumour (GIST) →](https://durgical.com/en/conditions/gastrointestinal-stromal-tumour/)
- Hypereosinophilic syndrome, chronic eosinophilic leukaemia, PDGFR-rearranged myelodysplastic/myeloproliferative disease, systemic mastocytosis and dermatofibrosarcoma protuberans.

## Adverse effects

### Common

- Oedema, especially around the eyes, and fluid retention
- Nausea, vomiting, diarrhoea, abdominal pain
- Muscle cramps and musculoskeletal pain
- Rash
- Fatigue

### Serious (rare, important)

- Severe fluid retention (pleural or pericardial effusion, rapid weight gain)
- Cytopenias: anaemia, neutropenia, thrombocytopenia
- Heart failure and left ventricular dysfunction
- Severe hepatotoxicity
- Gastrointestinal bleeding or perforation
- Severe skin reactions (Stevens-Johnson syndrome)
- Tumour lysis syndrome
- Growth delay in children

## Contraindications

- No absolute contraindications in the label; used with caution in heart disease, liver impairment and pregnancy

## Key interactions

**Strong CYP3A4 inducers (rifampicin, carbamazepine, phenytoin, St John's wort)**
Lower imatinib levels and can cause loss of response.

**Strong CYP3A4 inhibitors (ketoconazole, clarithromycin)**
Raise imatinib levels and toxicity.

**CYP3A4 substrates (e.g. simvastatin)**
Imatinib raises their levels.

**Warfarin**
Anticoagulation with heparin or low-molecular-weight heparin is preferred to warfarin.

**Levothyroxine after thyroidectomy**
Hypothyroidism can appear; TSH is followed closely.

## What is monitored

- Complete blood count, frequently in the first months
- Liver function before starting and regularly
- Body weight and oedema
- Kidney function
- BCR-ABL transcript levels (molecular response) in CML
- Growth in children

## Administration and safety

- Oral; taken with a meal and a large glass of water to reduce stomach upset.
- For people who cannot swallow tablets, the label allows dispersing them in water or apple juice just before taking them.
- Check the drug name carefully: imatinib, dasatinib and nilotinib are different drugs with different food and safety rules.
- Avoid grapefruit and St John's wort, which change its levels through CYP3A4.

## Pregnancy and breastfeeding

Can harm the fetus; effective contraception is used during treatment, and breastfeeding is not advised.

## Nursing care

- Weigh the patient regularly and look for periorbital and leg swelling; report rapid weight gain.
- Review blood counts and liver tests before refills as ordered.
- Ask about breathlessness, chest pain or black stools.
- Teaching: take it every day as prescribed, report fever or bleeding, use contraception, and be careful driving if dizzy or tired.

## Pharmacokinetics

**Absorption**
Oral; almost completely absorbed and taken with a meal and a large glass of water.

**Metabolism**
Liver, mainly CYP3A4, to an active N-desmethyl metabolite; it also inhibits CYP3A4 and CYP2D6.

**Elimination**
Mostly in the faeces as metabolites; a small part in urine.

**Half-life**
About 18 hours (about 40 hours for the active metabolite).

## Memory aid

«Imatinib aims at three»: BCR-ABL (CML), KIT (GIST) and PDGFR. Its tell-tale side effect is the puffy face (periorbital oedema).

## Test yourself

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

## What does imatinib inhibit in chronic myeloid leukaemia?

The BCR-ABL tyrosine kinase produced by the Philadelphia chromosome t(9;22).

## Which solid tumour responds to imatinib, and through which target?

Gastrointestinal stromal tumour (GIST), through KIT (CD117).

## A patient on imatinib gains weight quickly and has swollen eyelids. What is happening?

Fluid retention, a typical imatinib effect; it may progress to effusions and must be reported.

## Why can rifampicin make imatinib fail?

It induces CYP3A4 and lowers imatinib levels.

[Add to my cards (4)](https://durgical.app/estudiar/?add=/en/pharmacology/imatinib/)

[More Pharmacology questions →](https://durgical.com/en/practice/?f=pharmacology)

## What the labels mean

**High alert**
An error with this medicine can cause serious harm: double checks and protocols are used.

## Connections

## Related drugs 2

- [Dasatinib](https://durgical.com/en/pharmacology/dasatinib/)
- [Nilotinib](https://durgical.com/en/pharmacology/nilotinib/)

## Related conditions 3

- [Chronic myeloid leukaemia](https://durgical.com/en/conditions/chronic-myeloid-leukaemia/)
- [Acute leukaemia (AML and ALL)](https://durgical.com/en/conditions/acute-leukaemia/)
- [Gastrointestinal stromal tumour (GIST)](https://durgical.com/en/conditions/gastrointestinal-stromal-tumour/)

[← Back to the class: Kinase inhibitors (targeted oncology)](https://durgical.com/en/pharmacology/classes/kinase-inhibitors/)

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 - IMATINIB MESYLATE- imatinib tablet, film coated](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=a1787fad-3612-43e1-98fa-ce62361e0b3c) (DailyMed (U.S. National Library of Medicine), 2026); [Imatinib: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a606018.html) (MedlinePlus (U.S. National Library of Medicine), 2025); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=L01EA01) (WHO Collaborating Centre for Drug Statistics Methodology, 2026).

## **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/imatinib/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/imatinib/