[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [PARP inhibitors](https://durgical.com/en/pharmacology/classes/parp-inhibitors/) › Olaparib

# Olaparib

## PARP inhibitors?

PARP inhibitors

## High alert?

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

## Pregnancy: avoid?

Avoid in pregnancy. Can harm the fetus: a pregnancy test is done before starting, effective contraception is used during treatment and for a time afterwards (by women and by men…

The first PARP inhibitor: an oral drug for BRCA-mutated ovarian, breast, pancreatic and prostate cancers. Watch blood counts and the lungs.

Updated Nov 1, 2026

## Quick facts

**Group**
[PARP inhibitors](https://durgical.com/en/pharmacology/classes/parp-inhibitors/)

**Target**
Poly(ADP-ribose) polymerases PARP1 and PARP2

**Used for**
Maintenance in advanced · HER2-negative breast cancer

**Key effects**
Nausea · Fatigue and anaemia · Muscle

**Monitor**
Complete blood count at baseline · New cough

**ATC**
L01XK01

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

✂**Poly(ADP-ribose) polymerases PARP1 and PARP2**Olaparib

ⓘ The figure shows olaparib in the NAD+ site of the human PARP1 catalytic domain.

**Target in 3D:** Poly(ADP-ribose) polymerases PARP1 and PARP2. PDB structure 7KK4 (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/7KK4) · Drag to rotate · pinch to zoom

Olaparib inhibits PARP1, PARP2 and PARP3 by occupying the NAD+ site, and traps PARP on damaged DNA. Single-strand breaks persist and become double-strand breaks when the cell replicates. Tumours with BRCA1/2 mutations or other homologous recombination defects cannot repair them and die, while normal cells survive.

- Olaparib fills the NAD+ site and traps PARP on DNA
- Single-strand breaks become double-strand breaks
- BRCA-deficient cells cannot repair them and die

## Indications

- Maintenance in advanced or recurrent ovarian, fallopian tube or primary peritoneal cancer after a response to platinum chemotherapy (BRCA-mutated, or with bevacizumab in homologous recombination-deficient disease). [Ovarian cancer →](https://durgical.com/en/conditions/ovarian-cancer/)
- HER2-negative breast cancer with germline BRCA mutation: high-risk early disease after chemotherapy, and metastatic disease. [Breast cancer →](https://durgical.com/en/conditions/breast-cancer/)
- Maintenance in metastatic pancreatic cancer with germline BRCA mutation that has not progressed on first-line platinum. [Pancreatic cancer →](https://durgical.com/en/conditions/pancreatic-cancer/)
- Metastatic castration-resistant prostate cancer: alone with homologous recombination repair gene mutations, or with abiraterone with BRCA mutations. [Prostate cancer →](https://durgical.com/en/conditions/prostate-cancer/)

## Adverse effects

### Common

- Nausea, vomiting, decreased appetite, taste changes
- Fatigue and anaemia
- Muscle, joint and back pain
- Diarrhoea or constipation, heartburn
- Headache, dizziness, mouth sores, rash

### Serious (rare, important)

- Myelodysplastic syndrome and acute myeloid leukaemia (rare, often fatal)
- Myelosuppression: anaemia, neutropenia, thrombocytopenia
- Pneumonitis
- Venous thromboembolism, including pulmonary embolism

## Contraindications

- No absolute contraindications in the label apart from hypersensitivity; see the warnings

## Key interactions

**Strong CYP3A4 inhibitors (clarithromycin, itraconazole, ketoconazole, ritonavir) and grapefruit**
Raise olaparib exposure.

**Strong CYP3A4 inducers (rifampicin, carbamazepine, phenytoin, St John's wort)**
Lower its levels and can make it fail.

**Grapefruit, Seville oranges and their juices**
Can raise olaparib levels; they are avoided.

## What is monitored

- BRCA or homologous recombination test before starting
- Complete blood count at baseline and during treatment
- New cough, wheeze or breathlessness
- Signs of deep vein thrombosis or pulmonary embolism

## Administration and safety

- Oral; swallowed whole, never split, crushed, chewed or opened.
- Grapefruit, Seville oranges, their juices and St John's wort are avoided.

## Pregnancy and breastfeeding

Avoid in pregnancy. Can harm the fetus: a pregnancy test is done before starting, effective contraception is used during treatment and for a time afterwards (by women and by men with partners who could conceive), and breastfeeding is avoided.

## Nursing care

- Review blood counts before and during treatment; teach to report pallor, fatigue, bruising, bleeding or fever.
- Teach to report new cough, wheeze, breathlessness or fever.
- Teach the signs of a leg clot (pain, swelling) and of pulmonary embolism (chest pain, sudden breathlessness).
- Contraception for women and for men with partners who could conceive; men do not donate sperm during treatment and for months after.

## Pharmacokinetics

**Absorption**
Oral tablets, rapidly absorbed, with or without food.

**Metabolism**
Liver, mainly CYP3A4.

**Half-life**
About 15 hours.

## Memory aid

«Two roads to fix DNA»: BRCA already closed one, olaparib closes PARP, the other; with no road left, the tumour cell dies (synthetic lethality).

## Test yourself

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

## Why does olaparib kill BRCA-mutated cancer cells but spare normal cells?

Normal cells repair the resulting double-strand breaks by homologous recombination; BRCA-deficient cells cannot (synthetic lethality).

## In which four cancers is olaparib used?

Ovarian (with fallopian tube and peritoneal), breast, pancreatic and prostate cancer.

## Which rare but often fatal complication requires blood count monitoring on olaparib?

Myelodysplastic syndrome or acute myeloid leukaemia.

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

[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.

**Pregnancy: avoid**
Avoid in pregnancy. Can harm the fetus: a pregnancy test is done before starting, effective contraception is used during treatment and for a time afterwards (by women and by men…

## Connections

## Related drugs 4

- [Niraparib](https://durgical.com/en/pharmacology/niraparib/)
- [Rucaparib](https://durgical.com/en/pharmacology/rucaparib/)
- [Talazoparib](https://durgical.com/en/pharmacology/talazoparib/)
- [Abiraterone](https://durgical.com/en/pharmacology/abiraterone/)

## Related conditions 4

- [Ovarian cancer](https://durgical.com/en/conditions/ovarian-cancer/)
- [Breast cancer](https://durgical.com/en/conditions/breast-cancer/)
- [Pancreatic cancer](https://durgical.com/en/conditions/pancreatic-cancer/)
- [Prostate cancer](https://durgical.com/en/conditions/prostate-cancer/)

[← Back to the class: PARP inhibitors](https://durgical.com/en/pharmacology/classes/parp-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: [Olaparib: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a614060.html) (MedlinePlus (U.S. National Library of Medicine), 2023); [Olaparib - NCI](https://www.cancer.gov/about-cancer/treatment/drugs/olaparib) (National Cancer Institute, 2025); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=L01XK01) (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.

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