PARP inhibitor Pregnancy: Should not be used during pregnancy or in women of childbearing potential not using reliable contraception. Animal studies showed serious teratogenic effects and effects on embryofoetal survival. Pregnancy test before treatment; two forms of reliable contraception during treatment and for 6 months after the last dose in females; male patients must use a condom during treatment and for 3 months after the last dose and must not donate sperm during that period. Breast-feeding is contraindicated during treatment and for 1 month after the last dose.

Olaparib (Specialist drug)

Brand names: Lynparza

Olaparib is an oral PARP inhibitor used in oncology as maintenance or treatment for BRCA-associated ovarian, breast, prostate and pancreatic cancers; it is not a rheumatology drug.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: 300 mg (two 150 mg tablets) - total daily dose 600 mg

Route: Oral. Tablets must be swallowed whole and not chewed, crushed, dissolved or divided; may be taken without regard to meals

Frequency: Twice daily

Treatment should be initiated and supervised by a physician experienced in the use of anticancer medicinal products. The same 300 mg twice-daily dose applies as monotherapy and in combination with other agents. Biomarker testing is required before starting for several indications (BRCA1/2, HRD, pMMR status - see SPC). DOSE REDUCTIONS for adverse reactions: first to 250 mg twice daily (one 150 mg plus one 100 mg tablet, 500 mg/day), then to 200 mg twice daily (two 100 mg tablets, 400 mg/day). If a dose is missed, take the next normal dose at its scheduled time - do not double up. COMBINATION PARTNER DOSES quoted in the SPC: bevacizumab 15 mg/kg every 3 weeks; abiraterone 1000 mg orally once daily with prednisone or prednisolone 5 mg orally twice daily; durvalumab 1500 mg every 4 weeks; endocrine therapy per its own product information. DURATION: first-line maintenance in advanced ovarian cancer - up to 2 years if no radiological evidence of disease (may continue beyond 2 years if further benefit expected); adjuvant early breast cancer - up to 1 year; other indications - until disease progression or unacceptable toxicity. In prostate cancer, medical castration with an LHRH/GnRH analogue should continue unless surgically castrated. Not established in patients under 18 years - no posology recommendation can be made. Also this is the TABLET formulation (100 mg and 150 mg tablets); olaparib capsules are not interchangeable with tablets on a mg-for-mg basis - confirm the formulation before prescribing.

Dose adjustments

Renal

Mild impairment (creatinine clearance 51-80 mL/min): no dose adjustment. Moderate impairment (creatinine clearance 31-50 mL/min): 200 mg (two 100 mg tablets) twice daily, total daily dose 400 mg. Severe impairment or end-stage renal disease (creatinine clearance 30 mL/min or less): not recommended - use only if benefit outweighs risk, with careful monitoring of renal function and adverse events.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Hypersensitivity to the active substance or to any of the excipients
Breast-feeding during treatment and for 1 month after the last dose

Side effects

Nausea and vomiting
Fatigue/asthenia
Anaemia (Grade 3 or above in 14%)
Diarrhoea and decreased appetite
Neutropenia, leukopenia and thrombocytopenia
Headache, dysgeusia, dizziness, cough, dyspnoea and dyspepsia

Interactions

Strong CYP3A inhibitors: concomitant use not recommended; if unavoidable, reduce olaparib to 100 mg twice daily
Moderate CYP3A inhibitors: concomitant use not recommended; if unavoidable, reduce olaparib to 150 mg twice daily
Strong or moderate CYP3A inducers: avoid concomitant use - reduced olaparib exposure may reduce efficacy (US labelling)
Other myelosuppressive anticancer agents, including DNA damaging agents: potentiation and prolongation of myelosuppressive toxicity (US labelling)
Hormonal contraceptives: efficacy may be reduced (possible CYP2C9 induction) - an additional non-hormonal method should be considered

Clinical monograph

How it works

It inhibits poly(ADP-ribose) polymerase enzymes involved in DNA single-strand break repair, causing synthetic lethality in tumour cells deficient in homologous recombination, such as those with BRCA mutations.

Prescribing in practice

Haematological toxicity including anaemia, neutropenia and thrombocytopenia is the key concern, and rare cases of myelodysplastic syndrome or acute myeloid leukaemia have occurred, so a baseline and ongoing full blood count is essential and persistent cytopenias must be investigated.
It is a CYP3A substrate, so avoid strong CYP3A inhibitors and inducers where possible and adjust as advised in the SPC.
It is teratogenic and embryotoxic, requiring effective contraception during and after treatment.

Monitoring

Monitor full blood count monthly, watch for prolonged cytopenias suggestive of secondary malignancy, and assess renal and hepatic function and respiratory symptoms as guided by current prescribing references.

Counselling the patient

Take the tablets whole and report unusual tiredness, bruising or bleeding.
Use reliable contraception and tell us if you could be pregnant.
Mention new or worsening breathlessness or cough.

Evidence & guidelines

Its cancer indications are supported by randomised maintenance and treatment trials showing prolonged progression-free survival in homologous-recombination-deficient tumours.

Reference: multiple NICE TAs; SmPC; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

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