• HR-positive, HER2-negative advanced or metastatic breast cancer, in combination with:
    • Letrozole (first-line in postmenopausal women)
    • Fulvestrant (after progression following endocrine therapy)

Dosage:

  • 125 mg orally once daily for 21 consecutive days, followed by 7 days off (28-day cycle)
  • Used in combination with letrozole or fulvestrant
  • Capsules: 75 mg, 100 mg, 125 mg
  • Tablets (Ibrance®): same strengths; interchangeable with capsules but do not substitute milligram-for-milligram
  • Take with food, preferably at the same time each day
  • Swallow whole – do not crush, chew, or split
  • If a dose is missed, do not take an extra dose; take the next dose at the scheduled time
  • Class: CDK4/6 inhibitor
  • Mechanism of Action:
     Inhibits cyclin-dependent kinases 4 and 6 (CDK4/6), which blocks phosphorylation of the retinoblastoma (Rb) protein, resulting in G1 phase cell cycle arrest in cancer cells.
  • Metabolism: Liver (mainly via CYP3A4)
  • Half-life: ~29 hours
  • Excretion: Feces (~74%), urine (~17%)
  • Neutropenia, leukopenia
  • Fatigue
  • Nausea, diarrhea
  • Stomatitis
  • Alopecia
  • Infections (e.g., URTI)
  • Hypersensitivity to palbociclib or any excipients
  • Coadministration with strong CYP3A inhibitors or inducers, unless benefit outweighs risk
  • CYP3A4 inhibitors (e.g., ketoconazole, clarithromycin): ↑ palbociclib levels
  • CYP3A4 inducers (e.g., rifampin, phenytoin): ↓ efficacy
  • Avoid grapefruit or grapefruit juice

                                   Drug Status

Availability
Pregnancy
Breastfeeding
Schedule
BRAND NAME STRENGTH FORMULATION PACK SIZE MANUFACTURER DISTRIBUTOR
Ibrance 100mg Capsule 21’s Pfizer Labs Pfizer Labs
Ibrance 75mg Capsule 21’s Pfizer Labs Pfizer Labs
Ibrance 125mg Capsule 21’s Pfizer Labs Pfizer Labs