[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/) › Gefitinib

# Gefitinib

## 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.

A first-generation, reversible EGFR kinase inhibitor for lung cancer with EGFR exon 19 deletion or L858R mutation; typical effects are rash and diarrhoea.

Updated Nov 1, 2026

## Quick facts

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

**Target**
EGFR tyrosine kinase domain

**Used for**
First-line treatment

**Key effects**
Acne-like rash · Diarrhoea · Nausea

**Monitor**
EGFR mutation test before starting · New cough

**ATC**
L01EB01

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

✂**EGFR tyrosine kinase domain**Gefitinib

ⓘ The crystal shows gefitinib in the ATP pocket of the human EGFR kinase domain.

**Target in 3D:** EGFR tyrosine kinase domain. PDB structure 4WKQ (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/4WKQ) · Drag to rotate · pinch to zoom

Gefitinib competes with ATP and reversibly inhibits the EGFR tyrosine kinase, blocking receptor autophosphorylation and downstream signalling. It binds the activating mutations (exon 19 deletion, L858R) more tightly than the normal receptor, so EGFR-mutant lung cancers respond; resistance usually comes from the T790M mutation.

- Competes with ATP in the EGFR kinase
- Autophosphorylation is blocked (reversibly)
- Downstream growth signals stop
- Works in exon 19 deletion or L858R tumours

## Indications

- First-line treatment of metastatic non-small cell lung cancer with EGFR exon 19 deletion or exon 21 L858R mutation. [Lung cancer →](https://durgical.com/en/conditions/lung-cancer/)

## Adverse effects

### Common

- Acne-like rash, dry skin
- Diarrhoea
- Nausea, loss of appetite
- Raised liver enzymes

### Serious (rare, important)

- Interstitial lung disease
- Hepatotoxicity
- Gastrointestinal perforation
- Severe diarrhoea
- Keratitis and other eye disorders
- Bullous and exfoliative skin reactions

## Contraindications

- No absolute contraindications in the label

## Key interactions

**Strong CYP3A4 inducers**
Lower gefitinib levels.

**CYP3A4 inhibitors**
Raise gefitinib levels; the patient is watched for adverse effects.

**Proton pump inhibitors**
Raise gastric pH and reduce absorption; avoided if possible.

**Warfarin**
Bleeding and raised INR; INR is monitored.

## What is monitored

- EGFR mutation test before starting
- Liver tests periodically
- New cough, breathlessness or fever
- Diarrhoea, skin and eyes
- INR if on warfarin

## Administration and safety

- Oral; swallowed whole at about the same time each day.
- Check the name carefully: kinase inhibitors with similar «-tinib» names are not interchangeable.
- Proton pump inhibitors are avoided if possible.

## Pregnancy and breastfeeding

Can harm the fetus; effective contraception is used and breastfeeding is stopped.

## Nursing care

- Ask about breathlessness, cough and fever at each visit; sudden symptoms are reported at once.
- Review liver test results.
- Teaching: skin care and sun protection, report severe diarrhoea or eye pain, and use contraception.

## Pharmacokinetics

**Absorption**
Oral; with or without food; high gastric pH reduces absorption.

**Distribution**
Very wide tissue distribution.

**Metabolism**
Liver, mainly CYP3A4; CYP2D6 forms a metabolite, and CYP2D6 poor metabolisers have higher levels.

**Elimination**
Mainly in the faeces.

**Half-life**
About two days.

## Memory aid

Gefitinib and erlotinib are the «first generation» twins: reversible EGFR blockers, rash + diarrhoea, beaten by T790M.

## Test yourself

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

## Which patients with lung cancer benefit from gefitinib?

Those whose tumours carry EGFR exon 19 deletion or exon 21 L858R mutation.

## Which serious lung adverse effect requires stopping gefitinib?

Interstitial lung disease.

## Which genetic group of patients has higher gefitinib exposure?

CYP2D6 poor metabolisers.

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

[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 3

- [Erlotinib](https://durgical.com/en/pharmacology/erlotinib/)
- [Afatinib](https://durgical.com/en/pharmacology/afatinib/)
- [Osimertinib](https://durgical.com/en/pharmacology/osimertinib/)

## Related conditions 1

- [Lung cancer](https://durgical.com/en/conditions/lung-cancer/)

[← 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 - GEFITINIB tablet, film coated](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=3dd135f0-5db1-4236-9756-04533b66dc9d) (DailyMed (U.S. National Library of Medicine), 2026); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=L01EB01) (WHO Collaborating Centre for Drug Statistics Methodology, 2026).

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Representative model, for educational purposes only.

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