Palbociclib

IBRANCE

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Pronunciation: pal-boe-SYE-klib (EYE-brans)

Palbociclib ballicule: receptor binding, kinetics and half-life diagram — Mechanism of action: Palbociclib ballicule

What it isCDK4/6 inhibitor blocking cell cycle progression; hormone receptor-positive HER2-negative breast cancer.

Why this oneUnlike abemaciclib, it uses interrupted treatment and is limited by neutropenia rather than diarrhea.

What limits itNeutropenia governs treatment holds, though it rarely causes infection. CYP3A4 interactions can markedly alter exposure.

Palbociclib molecular structure (skeletal formula) — Molecular structure: Palbociclib

Palbociclib prescription history

Animated chart of estimated U.S. prescriptions per year, Oral anticancer meds (1953–2026). Palbociclib enters in 2015 (estimated).

FDA-approved for

HR-positive HER2-negative advanced breast cancer (2015)

Principal riskNeutropenia, which governs dosing

Classes and tags

Clinical profile

Therapeutic safety burden3 / 4

Overdose danger2 / 4

Weight-gain liability0 / 4

Sedation liability0 / 4

QT / Torsades0 / 4

Direct muscarinic antagonism0 / 4

Embryofetal risk3 / 4

Legacy pregnancy categoryUnknown / historical label unavailable

Defining liabilityMyelosuppression and agent-specific hepatic, cardiac, pulmonary, neurologic or reproductive toxicity require oncology monitoring.

FDA label

Read the full label on DailyMed ↗

NO BOXED WARNINGS

FDA dosing	Population	Start	Target	Max
HR+/HER2- advanced/metastatic breast cancer (+ endocrine therapy)	Adults	125 mg QD, 21 days on / 7 days off (28-day cycle)	125 mg QD	125 mg QD

Renal No adjustment for CrCl >15 mL/min (mild-severe)

Hepatic No adjustment for mild-moderate (Child-Pugh A/B); severe (Child-Pugh C): 75 mg QD

Instructions

Swallow tablets whole; do not chew, crush, or split
Take with or without food at approximately the same time each day
Missed dose or vomiting: do not take an extra dose; take next dose at usual time

Available strengths

cap 75, 100, 125 mg
tab 75, 100, 125 mg

Cautions

Neutropenia (monitor CBC)
Interstitial lung disease/pneumonitis (severe and fatal cases)
Embryo-fetal toxicity

Adverse reactions

Decreased WBC/neutrophils/hemoglobin/platelets
Infections
Increased blood creatinine, AST, ALT
Fatigue
Nausea
Stomatitis
Diarrhea
Alopecia

Pregnancy Can cause fetal harm based on mechanism and animal findings

Lactation No data; do not breastfeed during treatment and for 3 weeks after last dose

Cost

Palbociclib (IBRANCE)

Strength		#/mo	CostPlus
75 mg	tab	30 qd	not offered
100 mg	tab	30 qd	not offered
125 mg	tab	30 qd	not offered
75 mg	cap	30 qd	not offered
100 mg	cap	30 qd	not offered
125 mg	cap	30 qd	not offered

NADAC is a voluntary CMS survey of what retail community pharmacies pay for the drugs they stock. Palbociclib is dispensed outside retail pharmacies, so it rarely appears on surveyed invoices.

Generic entry2036 est.

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Self-check

Palbociclib: What toxicity limits treatment more than diarrhea?
Neutropenia.
Palbociclib: Which enzyme interactions can markedly alter exposure?
CYP3A4 interactions.