Ribociclib is a highly selective, orally bioavailable, small-molecule inhibitor of cyclin-dependent kinases 4 and 6 (CDK4/6). It is a targeted therapy used in combination with endocrine therapy for the treatment of hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) advanced or metastatic breast cancer. By inhibiting CDK4/6, it blocks the transition from the G1 to the S phase of the cell cycle, thereby inhibiting cellular proliferation in cancer cells.
Adult: 600 mg (three 200 mg tablets) orally once daily for 21 consecutive days, followed by 7 days off, to complete a 28-day cycle. Always administered in combination with endocrine therapy (aromatase inhibitor or fulvestrant).
Note: Take at approximately the same time each day, with or without food. Swallow tablets whole with water. Do not chew, crush, or split tablets. If a dose is vomited or missed, do not take an extra dose. Take the next dose at the usual time. Adhere strictly to the 21-days-on, 7-days-off schedule.
Ribociclib is a reversible, ATP-competitive inhibitor of CDK4 and CDK6. In hormone receptor-positive breast cancer cells, cyclin D1 forms a complex with CDK4/6, which phosphorylates and inactivates the retinoblastoma tumor suppressor protein (pRb). Phosphorylated pRb releases E2F transcription factors, driving cell cycle progression from G1 to S phase. Ribociclib inhibits this phosphorylation, leading to G1 phase arrest, thereby preventing DNA synthesis and cellular proliferation.
Pregnancy: Category D: Based on mechanism and animal data, ribociclib can cause fetal harm. Advise women of reproductive potential to use effective contraception during treatment and for at least 3 weeks after the last dose. Men with female partners should use condoms during and for 3 weeks after treatment.
Driving: May cause fatigue, dizziness, or vertigo. Patients should be cautioned about operating machinery or driving until they know how ribociclib affects them.
| Strong CYP3A Inhibitors (e.g., Ketoconazole, Itraconazole, Clarithromycin, Ritonavir) | Significantly increases ribociclib plasma concentration. Risk of severe toxicity (QT prolongation, neutropenia, hepatotoxicity). | Contraindicated/High |
| Strong CYP3A Inducers (e.g., Rifampin, Phenytoin, Carbamazepine, St. John's Wort) | Significantly decreases ribociclib plasma concentration. Risk of reduced efficacy. | Contraindicated/High |
| Drugs that prolong QT interval (e.g., Antiarrhythmics: Amiodarone; Antipsychotics: Haloperidol; Antibiotics: Moxifloxacin) | Additive risk of QTc prolongation and cardiac arrhythmias. | Major |
| Acid Reducing Agents (PPIs, H2 Blockers, Antacids) | Potential decrease in ribociclib solubility and absorption. Separate administration by several hours if necessary. | Moderate |
Same composition (Ribociclib (200mg)), different brands: