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CDK4/6 inhibitor

Palbociclib (Specialist drug)

Brand names: Ibrance

Palbociclib is a specialist oral targeted agent used with endocrine therapy in the treatment of hormone receptor-positive, HER2-negative advanced or metastatic breast cancer.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

Clinical monograph

How it works

It selectively inhibits cyclin-dependent kinases 4 and 6 (CDK4/6), preventing retinoblastoma protein phosphorylation and arresting the cell cycle to slow tumour cell proliferation.

Prescribing in practice

  • Neutropenia is the most common and dose-limiting adverse effect, so the full blood count must be checked before starting and during treatment with dose adjustment or interruption as required.
  • It is metabolised by CYP3A4, so avoid concurrent strong CYP3A4 inhibitors and inducers.
  • Patients should be advised to report signs of infection and venous thromboembolism promptly.

Monitoring

Monitor full blood count at the start of each cycle and as clinically indicated, and watch for signs of infection.

Counselling the patient

  • Attend for regular blood tests and report fever, sore throat or other signs of infection straight away.
  • Avoid grapefruit and grapefruit juice and tell your team about any new medicines.

Evidence & guidelines

Approval was supported by the PALOMA trials and is recommended by NICE in combination with endocrine therapy for advanced breast cancer.

Reference: NICE TA495; SmPC; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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